THE BOTS, OR OESTRI.

1 hese singular Insects, whose Habitations are the bodies of
living animals, are nourished in their Grub or Larva State in
an extraordinary way, by feeding upon the juices of these anir-
mals, and in their winged state often infest and teaze them,
that they could hardly fail of attracting notice, and becoming
an object of surprize and curiosity.

This curious race, with us in England, have obtained the
name of Botts, or, more correctly, Bots, as the origin of the
word would point out as. the more proper mode of spell-
ing it. The source or derivation of this appellation did not
till very lately occur to me, and was not at all apprehended
at the time I wrote an Essay on these Insects, addressed to the
Linnean Society, and inserted in the 3d Volume of their
Transactions. Our Lexicographers also appear to have been
at a loss respecting the true origin of this word, on which we
shall venture a suggestion that wi}l appear, we believe, tolera-
bly satisfactory. The derivation of it, we apprehend, is from
the French word Bout, signifying the extremity or end of a
thing, in the way we see it in the words About, Bottom, Bottle,
Botville, &c.; the last of these alluding to one living at the
end or extremity of a town, by elision or for brevity the u be-
ing omitted. From the same origin also we have Butts, houses
placed without or at the extremity or end of a town, the o in

Cktt/'T-U*)

PI. 2.

THE BOTS, OH OESTRT.

1 hese singular Insects, whose Habitations are the bodies of
living animals, are nourished in their Grub or Larva State in
an extraordinary way, by feeding upon the juices of these ani^
mals, and in their winged state often infest and teaze them,
that they could hardly fail of attracting notice, and becoming
an object of surprize and curiosity.

This curious race, with us in England, have obtained the
name of Botts, or, more correctly, Bots, as the origin of the
word would point out aa the more proper mode of spell-
ing it. The source or derivation of this appellation did not
till very lately occur to me, and was not at all apprehended
at the time I wrote an Essay on these Insects, addressed to the
Linnean Society, and inserted in the 3d Volume of their
Transactions. Our Lexicographers also appear to have been
at a loss respecting the true origin of this word, on which we
shall venture a suggestion that wijl appear, we believe, tolera-
bly satisfactory. The derivation of it, we apprehend, is from
the French word Bout, signifying the extremity or end of a
thing, in the way we see it in the words About, Bottom, Bottle,
Botville, &c.; the last of these alluding to one living at the
end or extremity of a town, by elision or for brevity the u be-
ing omitted. From the same origin also we have Butts, houses
placed without or at the extremity or end of a town, the o in

this case being for brevity omitted. Indeed the instances of
its application are very numerous in our language.

The way or reason that these Insects became so designated,
is pretty manifest, from the Habits more particularly of the
second species of this enumeration, or Hatmorrhoidalis, which
being fully fed its growth completed, in quitting its habitation
in the stomach, and passing through the intestines, does usually
bang for some days upon the margin of the Fundament, be-
neath the tail, then falling to the earth and forming a Chry-
salis ; and in this state would attract more particular notice
and attention, occasioning often serious inconvenience and dis-
tress. So situated and observed, it was denoted the Bout Worm
or End Worm, and by contraction Bot Worm ; and afterwards,
for want of better epithets, the appellation became extended to
the Fly produced by this worm, and we obtain Bot Fly, though
it is obvious, as the fly never affects these situations, its appli-
cation is improper, and has served to disguise and conceal the
real origin of the name.

Erroneous and strange notions were entertained in early times
of these animals. What views the Romans had of them, we
learn from a passage in Vegetius, an elegant veterinary writer
in the time of Valentinian, in the fourth century. He says,
" When a Humour is found in the anus of the Horse like a
boiled bean, it is a sign of this disease (the Coriago) or hide-
bound Horse, for it is a sanies from the wounds inflicted by small
animals in the inside of the beast ;*" in which it is evident he
alludes to the second species, the hemorrhoidal or red-tailed
Bot, which in hanging, as we have stated, to the extremity of
the rectum, corresponds very tolerably in size and appearance
to the boiled Bean he compares it to. Still more antiently than

* Hujusmodi passionis signum est (morbus coriaginosus) cum invenitur humor
in ano fabae coctse similis : est namque sanies ex illis vulaeribus que bestioke in-
trinsecus fecerunt. Ed. Manbeira, p. 63.

this does Moses in the sacred writings appear to allude to an
Insect of this tribe in Egypt, that caused great dread ; but of
what precise species this should be, we do not venture to make
any conjecture.

In the Georgics of Virgil the attack of the Ox-bot upon the
herd is strongly delineated, and perhaps correctly. The shrill
sound, however, which Virgil describes, we have not been able
to perceive ; and believe that the agony the fly occasions in
depositing the egg in the skin, will account sufficiently for the
violent agitation of the herd, without this sound. We, how-
ever, mention it, in order to direct the attention of others, who
may have the opportunity, to this circumstance, and to con-
firm or. reject this part of the poet's admirable description.
His lines are these :

" Est lucos Silari circa, ilicibusque virentem
Plurimus Alburnum volitans, cui nomen Asilo
Ronianum est, Oestron Graii vertere vocantes :
Asper, acerba sonans: quo tota exterrita sylvis
Diffugiunt armenta ; furit mugitibus aether
Concussus, sylvseque et sicci ripa Tanagri."

Georg. lib. iii. v. 146�151.

TRANSLATION.

" About the Alburnian groves, with holly green,

Of winged insects mighty swarms are seen;

This flying plague, (to mark its quality,)

Oestros the Grecians call�Asylus we�

A fierce loud buzzing breeze ;�their, stings draw blood,

And drive the cattle gadding through the wood.
^N Seiz'd with unusual pains, they loudly cry:

Tanagris hastens thence, and leaves his channel dry.

This curse the jealous Juno did invent,

And first employ'd for Io's punishment:

To shun this ill, the cunning leach ordains

In sultry summer heats, for then it reigns,

To feed the females ere the sun arise,

Or late at night, when stars adorn the skies."

Drydes.

The next notice of these animals in point of antiquity that we
have yet observed is with the Veterinary writers of Constantino-
ple, as Absyrtus, Theomnestus, &c. who appear to have designated
them by the term Teredines, {n^Smt,) perhaps on account of
their cylindrical figure ; or it may be from their boring, as they
apprehended, holes in the stomach, an apprehension and belief
which prevails very much at this day among the ignorant, but
is without foundation. The impressions or indentations they
occasion upon the soft internal coats of the stomach, are often,
it is true, pretty deep, but never, as far as we have seen, have
pierced through the stomach; these indentations probably
close and fill up again, after the Bot is removed; for the death
of animals is certainly not designed in their use,

The Veterinarians of Constantinople for their cure direct us
to extract them from the fundament with the fingers, and
then kill them by strewing hot ashes over them ; by which
recommendation it would appear that they entertained some
obscure apprehensions of their afterwards coming to something
hurtful, if permitted to live, though it is probable their notions
were very obscure, if they had any, of their real trans-
formations.

The same Veterinarians, I observe, have also made an allu-
sion to the Bot which infests the head of the Stag; of which,
excepting what Reaumur has informed us, we know no more
at this day than what they did, at least that I am acquainted
with. Reaumur describes it as existing in a sac of the Fauces.
What the complete Insect is, we are as yet unacquainted ; and
I mention it here to excite the farther prosecution of this
object, which to those who have leisure and opportunity, and

especially those situated near parks of deer, might find it an inte-
resting pursuit. These early Byzantine Veterinarians imagined
this Bot fell from the stomach into the head of the staff, whilst
the animal was in the act of grazing.*

Aristotle is also conceived to have alluded to these Insects
in the prefatory part of his history of animals, in the following
passage :�" There are, moreover, animals which first live in
water, afterwards, their form changed, they pass their lives out
of it, as the WaterGnats, and after the same manner come the
Oestros, which afterwards infest animals." Aristotle, it is
probable, used this term in a general sense for all such animals
of the fly kind as infest the Horse, without having in view
this Genus, as constituted by modern naturalists.f

Our ancestors of these isles, at no very distant period, enter-
tained notions as ill founded and vague as any the antients had
ever conceived ; for they supposed them somehow engendered
of putrefaction and corruption, and that poverty and bad diet
were favourable to their production. Blundeville wrote on
Horses in the reign of Queen Elizabeth, and his words respect-
ing them are these:�"And the third sort of worms be short
and thick, like the end of a man's little finger, and therefore
be called Truncheons, though they have divers shapes, accord-
ing to the diversitie of the place perhaps where they breede,
or else according to the figure of the putrified matter whereof
they breede : yet they no doubt proceed all of one cause, that
is to say, of a rawe, grosse, phlegmaticke matter, apt to putre-
faction, engendered most commonly by fowle feeding," &c.
Book III. chap. xcvi. p. 43.

Our great dramatist, Shakspeare, in the same manner, makes
the ostler at Rochester, in the play of Henry the Fourth, say

"* Editio Basiliffi, p. 142. Ibid. Latine reddita Ruellio, p. 55.
t Duval's Aristot. Lib. I. cap. i. Tom. II. p. 763.

thus :�" Peas and beans are as dank here as a dog, and that is
the next way to give poor Jades the Bots :" a happy descrip-
tion of the popular notions respecting them of those days ; and
the wretched nag of Petruchio, with his ill appearance and
poverty, is in true character described as " so begnawn with
the Bots."

Feai'ful apprehensions are entertained, even at this day, by
the ignorant ; for if, by any chance, they are presented with the
singular spectacle of the Horse's stomach having a cluster of
Bots hanging to it, they are almost sure to enumerate it among
the causes of his death, with expressions of horror, though
amply accounted for by the actual destruction of some viscus,
or other causes ; and seeing the coats of the stomach indented
and impressed where they adhered, they let imagination carry
them to the real perforation of the stomach, stating it as eaten
up, and gnawed through by them.

Knowledge, which usually unfolds her treasures to the labours
of the industrious and persevering, first dawned on this branch
of science in Italy, about the commencement of the last cen-
tury, when the discovery of the circulation of the blood gave
a zest to the studies of Anatomy, and called up much laborious
investigation of the structure of the bodies of animals ; and
the formation of the Royal Society held out an encouragement
and place of deposit for the labours of the inquisitive, and
brought about a more close and correct notice and considera-
tion of the various objects of nature.

Malpighi, as far as I yet know, was the first who undertook
to describe them intelligibly, though very briefly, and only the
Larva, in a paper or memoir laid before the Royal Society on
a different subject.* The Larvae he described were found in
the stomach of an Ass, and were probably those of the Oestrus

* Malpighi Opera, De Structura Glandularum Epistola, p. 9.

Equi. He went no farther than describing their general ap-
pearance.

Redi next took a more extended and particular notice of
them, giving some details of their history.*

At this early period of advancement in their knowledge
crept in error, from a too loose and careless observation, and
which was received and spread with its usual facility. Dr.
Gaspari propagated a belief, that these flies, to get their larvse
into the bodies of animals, entered by the fundament, and there
deposited their eggs ; a thing that was utterly impossible,
without their wings being mutilated or destroyed in the act:
and the account, though perfectly fabulous, was but too easily'
believed, and even by such naturalists as Vallisneri, Reaumur,
and Linneus himself, who says of the Hctmon-hoidalis, " Habi-
tat in ILquorum intestine recto, mire per anum intrans." Syst.
Nat. p. 970- These wonderful accounts, though erroneous,
might serve one useful purpose, by exciting the public curiosity
the more, and lead by this to a farther research into their
true Habits and History.

The first who took much pains in considering them was
Vallisneri, an Italian Physician of Padua, and the pupil of the
celebrated Malpighi. With great industry, perseverance, and a
care truly philosophic, he succeeded in exposing a large share of
their natural history ; he bred for the first time, atleast that we
know of, the perfect Fly from the Grub, in the backs of oxen,
and traced its transformations till it arrived at the winged
state, though only one, and in a very mutilated state. His
first Essay, however, was written upon the Bot of the Sheep,
which inhabits the frontal and maxillary cavities of this ani-
mal. He accompanied his account with coarse figures of them,
both of the Larvae and perfect Insects, His Essay appears to

* Redi Francis Esperimenti intorni agT Iosetti, p, 170.

have been written about the year 1712. Subsequently, in the
second volume of his Works, he gives some less accurate details
of the Horse-bots. The accounts of this indefatigable writer
are plentifully stored with Quotations from the Italian and
Latin Poets, in the passages in which he apprehended allusion
was made to these animals; and he unfortunately too implicitly
gave credit to his friend and countryman, Dr. Gaspari, respect-
ing their mode of propagation, which led others more readily
to believe in the same delusion.*

The truly ingenious Reaumur, in France, was, in point of
time, the next who studied the manners of these animals. He
repeated nearly all the experiments of Vallisneri, giving far-
ther details, and a better account of them, accompanied with
more correct figures. He succeeded, though with much
difficulty and labour, in obtaining two or three flies from the
Maggot of the Ox-bot. His details, though somewhat prolix,
are interesting ; but his matter, however, is not kept sepa-
rated from other objects, and we may observe that, if all the
very numerous subjects of natural history were so treated, no
ordinary time would suffice for the perusal of the volumes they
would extend through.

Linneus has usefully exhibited an example of conciseness
for these pursuits, which rebukes, as it were, the dilated details
of several writers in natural history of this period. The actual
fly of the Ox-bot has been truly rare, and difficult to obtain,
and is seldom met with in Cabinets of Insects ; and what is
singular is, it remained unknown to Linneus to the last, for he
described, through all the editions of the Systema Naturae,
the large Horse-bot with spotted wings, for it. I propose
hereafter, when I treat of this species in particular, to give an
account of a method I used for procuring this Fly, and that

* Vallisneri Opere Physico-Mediche, Venezia 1733, p. 217, et Vol. II. p. 1.

without much difficulty, by which any one may obtain it rea-
dily for his observations.

Reaumur, having pursued the Sheep-bot through its changes,
obtained from his own coach-horses the Larvas of the Hasmor-
rhoidal or Fundament Bot, and bred the Fly from it. He was
successful also in raising to the Fly state, another and more
rare species, the Oe. Veterinus, or Red Bot-fly; but, like Val-
lisneri, he was in doubt and perplexity whether they were
varieties or the same species. His figures are better than
"Vallisneri's, which were hardly cognizable or characteristic
enough to identify the species ; being taken, perhaps, from mu-
tilated specimens, or drawn without sufficient care, or from
the difficulty of finding artists at this period. But what is
most singular is, that neither of these celebrated naturalists
appear to have known our common large Horse-bot, (Oe. Equi,)
which made these writers much more difficult properly to
understand ; or if they knew it, they have at least not figured
or described it.

In a subsequent volume, Tom. V. of this ingenious writer,
(Memaires sur les Insectes,) he has given us an account of the
Bot of the Stag, at least the Grub or Larva, for the Chrysalis
or Fly he appears not to have known. He found these Larvae
in a sort of capsule or sac of the Fauces near the root of the
tongue, and it is probable we may possess in our cabinets the
perfect Insect of this Larva, which chance or accident may have
thrown in our way, without knowing what it is, as it has never
yet been bred through its different states, in order with cer-
tainty to identify it. Whether the Fauces or the large opening
of the Eustachian Trumpet into the Fauces of these animals, is
their proper habitation, we know not, or whether they crawled
thither after death, from the sinuses of the face or any other
parts, is uncertain. I have remarked, however, that those

Larva? which infest the Horse's stomach never let go their hold,
or move after the death of the animal, but are always found
fixed to the coats of the stomach, that this apprehension of
their moving after death is perhaps without real foundation.

To obtain certain information of this species, and procure
the Fly, would not be an unpleasing task, or difficult to exe-
cute, by one having leisure and the opportunity of a park of
deer for his observations. It Avould be only necessary for this
purpose to keep a few of these animals for the two or three
summer months, or through the months of June or July only,
in a confined place, having a smooth floor, or one boarded or
bricked, on which, by frequent search, the Larva fully grown,
and falling from the nose or mouth, or perhaps the anus, would
be easily discovered, and its advancement afterwards to the
perfect or winged state would be attended with little or no
trouble or difficulty. The Larva of this species, as figured by
Reaumur, has considerable affinity to that of the Sheep, but
is larger, and somewhat differently coloured. See Tom. V.
p. 6j, PI. 9, fig- 2, 6. I mention this the more particularly to
draw the attention of others to it.

The next who has given us any account of these Insects worth
noticing is Baron De Geer, an Envoy or Ambassador, we
believe him to have been, from the French Court to the Court
of Sweeden. He was eminently skilled in the natural history
of Insects, and was the intimate friend of Linneus. He de-
scribed the true Ox-bot, and the large Horse-bot, and was aware
of the Linnean error in respect to these two Insects, which it
is singular Linneus did not avail himself of, but, like an origi-
nal writer, he perhaps perused but little those that followed him.
De Geer, however, not having perhaps ever seen the Hcc.mor-
rhoidulis, confounded it with the Ox-bot, from the similarity
of its description. His figures are but indifferent, and very
inferior to those of Reaumur ; nor has he much more than

copied the remarks of Reaumur in respect to their history. He
has called the great Horse-bot Oestrus Intestinalis, a name we
cannot acquiesce in, as this species truly lives in the stomach,
and merely passes through the intestines in its way to the ground
to become a Chrysalis.

The next writer on this subject was Linnaeus himself, whose
acuteness, taste, and indefatigable research, the admirers of natu-
ral history will long have cause gratefully to remember. He fur-
nished us with some interesting details respecting the Rhein-deer
Bot, acquired during his tour in Lapland, and he marshalled,
for the first time, the members of this singular family, under the
generic title Oestrus, separating them from the other families of
flies, hostile to the repose of animals. He enumerated five spe-
cies, all European, as follows :�Oes. Bovis, intending to give the
Ox-bot, but described by mistake the large Horse-bot, with
spotted wings for it. The Oe. Tarandi, or Rhein-deer Bot. The
Hemorrhoidal, or Red-tailed Horse-bot. The Nasalis, for so he
termed the next species, from supposing that it entered and lived
in the larva state in the fauces or nostrils of the Horse, which,
as it now appears to be erroneous, we have ventured to set aside
the name, and to call it the Veterinus, as the former name if pre-
served would ever convey a false notion of its habits. The name
Veterinus signifying of or belonging to beasts of burden, and not
implying any precise place in respect to its habitation, we think
better suited to it, at least it may continue till its history is com-
pletely made out. Wanton change in names cannot be too much
reprobated ; but when a strong necessity, from actual research
and discovery, makes it necessary, it becomes a duty ; as specific
names are intended as aids, but not immoveable fetters, to natural
history.

His fifth species was the Oestrus Ovis, or Sheep-bot. The num-
ber has since been more than doubled by succeeding writers.

After Linnaeus followed a considerable number of detached
notices of these Insects, by various writers of Fiance, Germany,
and Sweden, without adding much to our knowledge of them ;
as Geoffroy, Wohlfarht, Fischer, Leske, Ross, Villers, Sultzer,
Frisch, Modeer, &c.

An entomologist of great eminence, J. C. Fabricius, of Kiel,
in Holstein, is the next we have to notice as a writer on this sub-
ject. He was a pupil of Linnaeus, and indefatigable in describing
and adding to the enumerations of his great master, the Insects
which the numerous collections and cabinets of Europe afforded,
and by which he has vastly increased the numbers described by
his predecessor, and his descriptions and nomenclature are often
truly excellent. In his last work the Systema Entornologia Emen-
data, he has, however, obscured this genus in a way that it will
not be easy to unravel. He has given an Oestrus Bovis, with a
description nearly corresponding to the true one, alls immaculatis,
&c. but immediately refers to the Linnean Bovis alls maculatis,
and continues the Linnean references.

Under the title of Equi, he has described the Oe. Veterinus,
under which the Hasmorrhoidalis is introduced as a variety P ; so
that a description of our common Oe. Equi, is altogether omitted
as a species, at the same time the variety of it, (3, of my account,
and of the Linnean Fauna Suecica, is presented as a distinct spe-
cies, under the strange title of Oe. Vituli, as though calves were
subject to them ; and beneath it again is a reference to the true
Equi of Geoffroy.

The commission of errors like these, in a genus whose species
had been more numerous, might have defied the possibility of
detection, whilst the patient investigator might endeavour to
understand them with unavailing labour. Nor can I observe
without regret, in this respectable work, such a direct abuse of
the intention of synonyma, which far from assisting as auxiliaries

to the description which they ought to do, serve only to perplex
by their perfect disagreement. His generic characters of this
genus are also false, as though made by guess more than exami-
nation.

It has been doubted whether these animals possess any mouth :
Linnaeus expressly says, " Os nullum punctis tribus;" but when
the hairs are removed, which in every species very much obscure
the parts of the mouth, two clavated palpi are seen, and between
them the opening of the mouth ; and by laying open the vesicular
or inflated part of the face, the continuation of it is visible in
the form of a membraneous haustellum, which is generally co-
loured with some dark brown matter lodging on the inside ; though
I-confess, after repeated dissections, I have not been able to trace
this haustellum farther than the inside of the inflated part of the
head, whei*e it appears to enlarge and terminate.

Fabricius has minutely described labia to the haustellum, and
other apparatus to the mouth, which I have not been fortunate in
obtaining a sight of. At the same time I cannot help being sur-
prized that he should have overlooked the palpi, which he ex-
pressly denies the existence of, though tolerably visible even
without the aid of glasses.*

He added also to his enumeration the Oe. Trompe and the Oe,
Pecorum, and one or two of the American species of Bots, or
rather subtercutaneous flies, which on more minute inspection we
are induced to separate from this genus, and form them into a
new family, under the generic title Cuterebra, three species of
which we propose to give, for the first time with figures.

After Fabricius, Professor Gmelin published an enlarged edi-
tion of the Systema Naturce, and collating from all quarters, vastly
enlarged in appearance the extent of this family ; but untortu-

# Fetbricii Genera Insectqrum.

nately copying from books, without any knowledge of the ani-
mals themselves, he fell into numerous errors. Three species he
added to the enumeration of Fabricius, from the works of Pallas,
viz. Oe. Anteiopcc, Fascicuiosus, and Hominis, which there is much
reason to believe from his descriptions are all false ; and instead
of placing the Equi in the name of Bovis, as his excellent original
had done, we find the hctmorrhoidalis ; and by placing the Equi
again in the name of hemorrhoidals, and mixing the references
to each, an almost inextricable labyrinth of confusion is the con-
sequence, while the true Bovis still escapes undescribed, unless as
being the same as hcemorrhoidalis.

The mistake of hcemorrhoidalis for Bovis arose probably from
their similarity in description, in which they certainly interfere
very much ; though no two species can be more distinct when
seen together than these. This will ever be the bane of mere
compilation in natural history.

In continuing to the present time this brief view of their his-
tory, or the detection of their habits, I am necessarily led to
notice a memoir or essay of my own, formerly transmitted to the
Linnean Society, and published in the 3d volume of their Trans-
actions, p. 289, of which I consider this present work as only a
more digested and extended account. This was in the year 1796,
or about nineteen years ago ; and which memoir, as it adds a few
new discoveries respecting them, concludes this historical view of
the developement of their habits.

We are led to apprehend, that this family may be usefully
divided into three sections or subdivisions, according to the dif-
ferent parts or situations in the body the Larvas inhabit, viz. the
Gastricola;, or those which inhabit the stomachs of animals. It

separates those of the Horse from all the other species. The
next division will be the Cuticolce, or those which live in their
Larva state beneath the skins of animals ; and the third the Cavi-
colce, or those living in the cavities of the face. Perhaps a fourth
divisionmight be constituted, including those of the Fauces, if the
accounts we at present entertain of them be true, and the nerves
of the wings of these different families appear also to afford cha-
racters for these divisions, which was first observed to me by my
friend Dr. Leach.

The large Horse-bot being the most interesting to us in this
country, T shall begin my account with that species, and follow
it with the other species of that division.

Of the Oestrus Equi, or Large spotted winged Horse-bot.

As it is necessary to break into the circle of its history at some
point, I shall begin with an account of the egg, and its depo-
sition upon the skin of the legs of the horse, which is done in
the following remarkable manner :�When the female has been
impregnated, and the eggs sufficiently matured, she seeks
among the horses a subject for her purpose, and approaching him
on the wing, she carries her body nearly upright in the air, and
her tail, which is lengthened for the purpose, curved inwards and
upwards : in this way she approaches the part where she designs
to deposit the egg ; and suspending herself for a few seconds
before it, suddenly darts upon it, and leaves the egg adhering to
the hair : she hardly appears to settle, but merely touches the
hair with the egg held out on the projected point of the abdomen.
The egg is made to adhere by means of a glutinous liquor se-
creted with it. She then leaves the horse at a small distance,
and prepares a second egg, and, poising herself before the part,
deposits it in the same way. The liquor dries, and the egg be-

comes firmly glued to the hair : this is repeated by these flies till
four or five hundred eggs are sometimes placed on one horse.

The skin of the horse is usually thrown into a tremulous motion
on the touch of this insect, which merely arises from the very
great irritability of the skin and cutaneous muscles at this season
of the year, occasioned by the heat and continual teasing of the
flies, till at length these muscles appear to act involuntarily on the
slightest touch of any body whatever. See PL I. fig. 1.

The inside of the knee is the part on which these flies are most
fond of depositing their eggs, and next to this on the side and
back part of the shoulder, and less frequently on the extreme
ends of the hairs of the mane. But it is a fact worthy of atten-
tion, that the fly does not place them promiscuously about the
body, but constantly on those parts which are most liable to be
licked with the tongue ; and the ova, therefore, are always scru-
pulously placed within its reach. Whether this be an act of rea-
son or of instinct, it is certainly a very remarkable one. I should
suspect, with Dr. Darwin,* it cannot be the latter, as that ought
to direct the performance of any act in one way only. Which-
ever of these it may be, it is, without doubt, one of the strongest
examples of pure instinct, or of the most circuitous reasoning any
insect is capable of.

The horses, when they become used to this fly, and find it does
them no injury, as the Tabani and Canopes, by sucking their
blood, hardly regard it, and do not appear at all aware of its insi-
dious object. During warm sunny weather this process is seen
performed on commons, and in the fields.

The eggs thus deposited, (see fig. 2, and when magnified fig. 3,)
I at first supposed were loosened from the hairs by the moisture
of the tongue, aided by its roughness, and were conveyed to the
stomach, where they were hatched : but on more minute search

* Zoonomia. Vid. Chapter on Instinct,

I do not find this to be the case, or at least only by accident;
for when they have remained on the hairs four or five days they
become ripe, after which time the slightest application of warmth
and moisture is sufficient to bring forth in an instant the latent
larva. At this time, if the tongue of the horse touches the egg,
its operculum is thrown open, and a small active worm is produced,
which readily adheres to the moist surface of the tongue, and is
from thence conveyed with the food to the stomach. If the egg
itself be taken up by accident, it may pass on to the intestinal
canal before it hatches ; in which case its existence to the full
growth is more precarious, and certainly not so agreeable, as it is
exposed to the bitterness of the bile. I have often had proof of
this by making the following experiment with the eggs.

With a pair of scissars I clipped off some hairs with the eggs
on them from the horse, and on placing them in the hand, moist-
ened with saliva, they have hatched in a few seconds. At other
times, when not perfectly ripe, the Larva would not appear,
though held in the hand under the same circumstances for several
hours ; a sufficient proof that the eggs themselves are not con-
veyed to the stomach. See fig. 4.

It is worthy of remark, that it is probable the greater part of
the ova deposited by this fly, are taken up in consequence of the
irritations of other flies, as the Canopes, Tabani, and Muscat, who,
by perpetually settling on the skin, occasion a horse to lick him-
self in those parts, and thus receive the larva; on the tongue and
lips ; and a horse that has had no ova deposited on him, may
yet have the Bots, by performing the friendly office of licking
another horse that has. The eggs on the shoulder are particu-
larly well disposed for being received in this way.

It is fortunate for the animals infested by these Insects, or
rather most beautifully ordained, that their numbers are much
reduced, and kept within due limits, by the hazards they are
exposed to in the singular round of their propagation. I should

suspect near an hundred at least are lost for one that arrives at
the perfect state of a fly. In the first place, in the depositing
the eggs not a little interruption is given to the female by the
movements of the Horse : the eggs when deposited may remain
on the hairs untouched by the animal, unless some casualty makes
him lick those parts to which they adhere, and when ripe, or if
hatched and opened by rain, or other moisture, the larvae may
come forth, and crawl about till they die.

In the mouth of the animal they have the dreadful ordeal of
the teeth and mastication to pass through. On their arrival at
the stomach, they may pass, mixed with the mass of food, into
the intestines ; and, when full grown, on dropping from the anus
to the ground, a dirty road or water may receive them. If on
the commons, they are in danger of being crushed to death, or
of being picked up by the birds, who so frequently for food attend
the footsteps of the cattle. By such contingencies as these,
Providence has wisely prevented their too great increase, and the
total destruction of the animals they feed on.

The egg is glued on the hair with the broad end downward,
(see fig. 2, 3,) and is thus well disposed for the Operation of the
tongue in removing the operculum. This operculum is of an
oval figure, surrounded with a prominent margin. The micro-
scope shews the case of the egg to be shagreened in squares, or
divided by lines longitudinally and transversely disposed.

Of the Larva or Grub of the Oestrus Equi, or spotted Horse Bot.

At its first hatching it is, as we have observed, a small active
worm, long in proportion to'its thickness, but as its growth ad-
vances, it becomes proportionably thicker and broader, and
beset with bristles.

Some of these Larva?, when about two-thirds grown, are
represented in Plate I. fig. 5, adhering to the stomach. They are

very frequent in horses that have been at grass, and are in general
found adhering to the white insensible tissue or coat of the sto-
mach which comes from the lining of the oesophagus, and which in
extending or leading over the upper part of the stomach, repre-
sents, or is similar to, the maw or first stomach of the ruminating
animals. I do not recollect ever seeing many situated on the red
membranes of the stomach, which are, without doubt, more
sensible, and where their effects would have been more disagree-
ably felt.

They make small deep round holes where they adhere to this
white tissue, and sometimes so deep as to pass through it but not
through the other layers or coats of the stomach, as has been often
hastily apprehended and asserted, that they are probably but lit-
tle felt by the animal. In proof of this, I once gave six, and after-
wards twenty-seven, of the full grown Larvae to a horse, wrapt up
in balls of meal, but the horse by no external indications showed
any uneasiness in consequence.

They usually hang in dense clusters to this white cuticular
lining of the stomach, and maintain their hold by means of'two
<iark brown hooks, {see fig. 10, Plate I.) between which a longi-
tudinal slit or fissure is seen, which is the mouth of the Larva.
When removed from the stomach by the fingers by a sudden jerk,
so as not to injure them, they will, if fresh and healthy, attach
themselves to any loose membrane, and even to the skin of the
hand. For this purpose they sheath or draw back the hooks
almost entirely within the skin, till the two points come close to
each other ; they then present them to the membrane, and keep-
ing them parallel till it is pierced tbrough, they expand them in
a lateral direction, and afterwards, by bringing the points down-
wards towards themselves, they include a sufficient piece of the
membrane, to remain firmly fixed for any length of time as at an-
chor, without requiring any further exertion.

These hooks, the better to adapt them to this purpose, appear

to have a joint near their base. The Larvae of CE. Hcemorrlwidalis
and Ovis, and probably all those which feed on the mucous mem-
branes lining the internal canals of the body, are also furnished
with these tentacula ; whilst those Larva; which inhabit beneath
the skins of various animals will be found universally without
them, being confined in the capsule of the skin sufficiently secure.

The body of this Larva (see fig. 6, Plate I.) is of a whitish red
colour, and appears to be composed of eleven segments, sur-
rounded with a double row of horny bristles, a longer and a
shorter series, and placed alternately. The two last segments
appear naked, or destitute of them. These spines are of a reddish
colour, except the points, which are black, and are directed to-
wards the tail or large end of the Larva ; they are longer below
or on the belly of the Larva, than above or on the back, but are
still longer at the sides. By means of these they probably regain
their situation, if at any time they are detached from their hold,
by forcing them against the surrounding membranes, and are
assisted by the two crotchets or hooks at the head. I once met
with some of these in the duodenum, close to the pylorus, hav-
ing been carried perhaps into the intestines by some casualty,
and could not again regain completely their situation in the
stomach.

The aperture of the mouth appears surrounded with a promi-
nent margin, and is irregular and harder than the rest of the
skin ; but whether hard enough to masticate and feed on the vege-
table matters in the stomach, may be a question. Their food is
most probably the chyle, or, as it is in this state by some modern
anatomists termed chyme, or an imperfect sort of chyle, which
being nearly pure aliment, it is probable aifords but little excre-
mentitious residue. That it is the gastric chyle and not the
vegetable matter that they feed upon, is also rendered probable
from the support of the other species of this genus on purely
animal secretions.

At figure 11 is seen a convoluted tube, which, in dissecting one
of these, once presented itself to me, and which I apprehended
was the alimentary canal or intestine of the Larva.

On opening the body of the Bot, and removing the gelatinous
matter, the air tubes are seen, of a splendid silvery colour, or as
though injected with pure quicksilver. Their appearance is sin-
gularly beautiful, especially if the Bot be alive, or recently dead;
and it was in reality what first attracted my attention to these
objects, for if dead, and kept some time, these tubes become dull,
and of a brown colour. This glittering appearance arises from
the air being seen through the semitransparent pearly refracting
coats of the vessel. They remain distended by their own inhe-
rent elasticity, and are filled with air to their minutest ramifica-
tions. These branches often run up and down in the gelatinous
matter, in directions nearly parallel to the principal trunk.�See
fig. 11.

These trachea? or air pipes are eight in number in this Larva,
and their disposition is endeavoured to be represented at fig. J.
The two smaller ones, exterior to the central circle of larger
ones, appear to communicate with two small prominent nipples
or points upon the first segment, which are seen in fig. 10.

These tracheae or air tubes open into one common reservoir, at
the large end of the Larva, beneath a singular plate, fig. 9, of a
cartilaginous or horny consistence, having six semicircular lines,
with their points curved and opposed to each other ; these lines
are also made up of alternate depressed and elevated spots of
black and white ; and at this blunt extremity are also seen two
protuberant lips or sacs, filled with a watery fluid, which meet
and serve to close over and cover up this horny plate.�See
fig. 8.

Through this plate the air is perhaps admitted into these tubes,
the branches of which appear to terminate in the skin, the gela-
tinous matter, and upon the viscera. In most Larvae of the fly

kind, or of the dipterous order of insects, there are two dis-
tinct plates at this obtuse end, as may be seen in the common
maggot of the house fly and the blow fly. Keller, however, sup-
poses, and it is generally apprehended, and perhaps truly, that
the air is not received at this large end, but at the extremities or
terminations of these branches in the skin, forming on the sides,
what are called the spiracula.

The lips at the obtuse end of the Bot seem designed to conceal
and cover this horny plate, and defend it from the liquors of the
stomach, or clean and clear it of these gastric fluids or other
matters when necessary. In the Larva of the CEs. Ovis, or
Sheep Bot, this respiratory plate is not covered with lips in this
way, but is surrounded by a prominent margin or extension of
the skin, which closes over the plate, at the will of the animal,
and on opening again suddenly, is often attended with a distinct
snap, that may be heard to some distance. These lips as we
have stated appear to be mere membranous bags, and filled
with lymph only, which renders it probable that they are solely
for the convenience of the Larva, and form no part in the future
Insect, as are probably nearly or quite all the parts connected
with the skin.

Respiration appears to be the office of these air canals, which
are the lungs of the Larva ; and, considered in this point of view,
they are much larger than the respiratory organs of any other
animal: which is the more extraordinary, if the purpose of respi-
ration in animals be the production of animal heat, as the later
chemists suppose, this being altogether unnecessary to Larva3 that
are supplied so abundantly with it from the high temperature of
their residence in the living stomach ; nor can these organs be
formed for the purposes of the future insect, since they cannot
be detected in either the Chrysalis or Fly. The permeability of
these respiratory vessels to oxygen gas, is also to be taken into
the account. They would appear to be in these animals stouter

and less permeable than are the cells of the lungs formed of a
thinner membrane.

I have since found that air vessels of a similar structure may
be detected in the Larvae of most insects, as well in those that are
not exposed to any extraordinary temperature as those that are j
they are, therefore, not constructed with any view to these sin-
gular situations.

From the superior magnitude of the respiratory organs in most
of the Larvae of insects, one should be almost led to imagine that
the respiration in all animals was more intimately connected with
the reception of food, and the converting it into living matter*
than any other design.

In corroboration of this we may observe, that while the respi-
ratory organs are so large in the Larvae, they are remarkably
small in the perfect insect, which also, in general, has occasion
for very little food.

Perhaps the superior size of the air vessels of the Bot, com-
pared with the Larvae of other insects, arises from the greater
rarefaction and impurity of the air it is exposed to in the sto-
mach, which may render a larger portion of it necessary.

Whilst upon this subject it may not be improper to notice the
air vessels of the Larva of the Musca pendula, which are con-
structed in a very different way from any others I have seen.
The two principal trunks in this Larva are made up of semi-
circular cartilaginous rings or fibres, which are disposed in a spi-
ral direction, so as to form the tube. It is evident by this struc-
ture, that the area of the tube may be entirely obliterated, and
the sides be brought into contact.

The convenience attending this structure, to a Larva living in
putrid fluids of considerable depth, appears to be, that beside
its use in respiration, it may serve the same office as the air blad-
der in fishes, regulating by its contraction or expansion the den-

sity or rarity of the included air, and consequently the descent
or ascent of the Larva in those fluids.

These Bots, as is also the case with two or three other species,
pass the autumn, winter, and spring months in the stomach, and
arrive about the commencement or middle of the summer at their
full growth, requiring a twelvemonth fully to complete their struc-
ture. The slowness of their growth and the purity of their food
must occasion what they receive in a given time to be proportion-
ably small; from whence probably arises the extreme difficulty
there is found in destroying them by any medicine or poison thrown
into the stomach. After opium had been administered to a
horse labouring under a case of locked jaw for a week, in doses
of one ounce every day, on the death of the animal I have found
the Bots in the stomach perfectly alive. Tobacco has been em-
ployed in much larger quantities in the same complaint, and has
been also longer continued without destroying them. They are
also but rarely affected by the drastic purgatives which bring
away in abundance the Tenice and Ascarides.

It is to be remarked, these Larvae probably never change the
skin, which is very dense and tough, and becomes at last the
shell of the Chrysalis ; and we may therefore discover upon the
Chrysalis all the points and lineaments of the Larva dried up and
diminished, in most other insects a cuticle separates from the skin
at the time of this change. The small end of the Chrysalis, in all
the species of this genus, contains the head of the Fly, the
contrary being the case with almost all other insects.

This species, though common with us in England in the Fly
state, in the Chrysalis state is rare and difficult to procure ; and
for this reason, that the Larva when full fed and grown to its
size, escapes from the stomach and through the intestines, with-
out making any stay or lodgment at the fundament, as the next
species does, which affords us the more easy opportunity of pro-

curing it. The specimens which I have obtained of its Chrysalis
have been found upon the ground, or under horse dung ; its ap-
pearance is given PI. I. fig. 12.

It is fortunate for the animal, or rather we should say it is beau-
tifully ordered and provided, that the Larva of this species should
make no stay at the edge of the anus, as far at least as we have
yet observed, and as is the case with the next species ; for it is
obvious, had it so done, its roughness and more considerable
dimensions would have rendered it a very serious evil.

Whether these Larva; can exist in the stomach of a carnivo-
rous animal I am not certain. I gave upwards of a hundred eggs
(proved by trial to be ripe, and containing a living caterpillar,)
to a cat in milk at various times ; and on destroying her at
the end of two months after the first portion had been given,
no traces of them in the stomach or intestines could be dis-
covered ,

I have once seen the Larva of this Oestrus in the stomach of an
ass : indeed there is little reason to doubt their existence in the
stomachs of all this tribe of animals.

The Larva, when matured and ripe, quits the stomach of the
animal, and falls to the ground, and finding a convenient place of
retreat, undergoes its change to Chrysalis, the skin then losing its
organization, and changing its colour to a reddish brown. After
remaining torpid in the state of Chrysalis a few weeks, the super-
fluous moisture being removed, and the parts of the future Insect
being hardened by drying, it bursts from its confinement, and the
Fly appears making its exit at the small end, (see fig. 13 and 14,
the male and female,) and the head or face of the Fly very much
enlarged, fig. 15, and one of its wings magnified, showing the
distribution of its tendons or nerves, fig. 16.

On quitting their shell they in a few hours become dry, take
wing, and then seek their mates. The female being impreg-
nated, searches for a proper subject among the Horses, performs

with great solicitude and care her office of depositing the eggs on
the legs of the Horse, in the manner we have already stated ;
thus completing the wonderful round of its operations and his-
tory, which sometimes I have thought might not afford a subject
altogether unworthy of the poet's pen, being novel, innocent, and
full of singular incident; and if mingled with the probable designs
of an all-wise Providence in thus providing for them, and <4heir
probable benefits to the animal in return for their habitation, and a
description of the dangers and solicitudes attending the process
of their birth and breeding: the rural scenery of the places of
their resort, and of these exploits, and with useful reflections
arising from such incidents, it might be rendered perhaps, in
good hands, not destitute of interest and amusement.

There is considerable difference in the male and female Fly; the
extremity of the abdomen in the one is obtusely abbreviated, in
the other drawn out to a style or horny tube of some length, for
the more convenient depositing the eggs and applying them to the
hair.�See fig. 1. PI. I.

The perfect Fly but ill sustains the changes of weather ; and
cold and moisture, to any considerable degree, would probably
be fatal to it. It is remarkable these flies never pursue the horse
into the water. This aversion I imagine arises from the chilness
of that element, which is probably felt more exquisitely by them,
from the high temperature they had been exposed to during their
Larva state in the body of the animal. The heat of the stomach
of the horse is much greater than that of the warmest climate,
being about 102 degrees of Fahrenheit, and in their fly state they
are only exposed to 60, and from that to about 80 degrees. This,
change, if suddenly applied, would, in all probability, be fatal
to them ; but they are prepared for it, by suffering its first effects
in the quiescent and less sensible state of a Chrysalis. I have
often seen this Fly during the night-time, and in cold wea-
ther, fold itself up, with the head and tail nearly in contact,

and lying apparently m a torpid state, though in the middle of
summer.

To prevent unnecessary repetition, these Flies are described
Math the other species, both in English and Latin, at the conclu-
sion of this Essay.

On the Oestrus Hjemorrhoidalis, or Fundament Bot.

I shall begin my account of this species at the same point as
the former, with the deposition of the egg, the manner of which,
I apprehend, has never been described or known before.

This proceeding I have frequently witnessed, and it may be
seen by any one desirous of observing so curious a fact upon most
of the commons of this country. About Ditton, Molesey, and
Esher, I have more particularly seen it where the cattle are
much annoyed with it ; and I once also saw this same operation
in the fertile meadows of Holland, near to Groningen, while be-
ing conducted a prisoner through this country to Amsterdam, and
I have caught the Fly more than once in the very act in my
hands.�See fig. 17. PI. I.

The part chosen by this Insect for this purpose is the lips of
the Horse, which is very distressing to the animal from the exces-
sive titillation it occasions ; for he immediately after rubs his
mouth against the ground, his fore-legs, or sometimes against a
tree, with great emotion ; till the animal at length finding this
mode of defence insufficient, enraged he quits the spot, and
endeavours to avoid it by galloping away to a distant part of the
field ; and if the Fly still continues to follow and tease him, his
last resource is in the water, where the Oestrus never is observed
to pursue him. These flies appear sometimes to hide themselves
in the grass ; and as the horse stoops to graze they dart on the
mouth or lips, and are always observed to poise themselves dur-

ing a few seconds in the air, while the egg is preparing on the
extended point of the abdomen.

When several of these flies are confined in a close place, they
have a particularly strong musty smell ; and I have observed
both sheep and horses, when teased by them, to look into the
grass and smell to it very anxiously ; and if they by these means
discover the Fly, they immediately turn aside and hasten to a dis-
tant part of the field.

I once saw in a meadow or field upon the cliffs at Margate, a
Fly of this sort teasing a Horse that was confined to a small space
by a spike stuck in the ground, to which a cord was tied. He
could not get away from its attack, and became quite furious, for
in kicking at the Fly with his fore-foot, which he did vehe-
mently, he often struck the bone of the lower jaw, creating
excessive pain ; for in that direction while grazing the Fly comes
to the beard of the .lower lip.

The eggs of this species are difficult to be seen upon the
Horse's skin or beard, owing to the agitation of the beast, and
from the colour of the egg being dark like that of the skin of the
Horse. The animal has been generally too impatient, while un-
dergoing this operation, for to let me examine them very well.
I ascertained, however, its form by pressing one of these eggs from
the abdomen, which had somewhat the appearance and figure
represented at 18, having a kind of petiolus or stalk to it, and its
blunt extremity obliquely trancated and curved.

The Larva or grub of this species inhabits the stomach as the
former, generally adhering to the white lining, and is disposed
promiscuously in dense clusters, after the same manner ; they may
however be distinguished from them by being in general smaller,
longer in proportion to their bulk, and rounder ; and I have
thought of a duller red, or more inclining to white, than those
of the Equi, for they differ in appearance in different subjects.

This species was more particularly known to Reaumur and
Vallisneri, and is the same about which Gaspari was led to pro-
pagate his wonderful accounts of the Fly actually entering the
body of the animal to deposit its eggs, a thing on several ac-
counts impossible ; for, in the first place, it is to be remarked,
that no anintal of this description is so unwise as to commit an
act of severe and deliberate punishment upon itself, and of self-
destruction, for all its members must have been broken by passing
the strong sphincter of the Horse's rectum ; or if the rectum
was first protruded, and, as they pretended, entering at this
moment, he became enclosed among its folds, he would be so
unfavourably situated, being surrounded with slime, wetted, and
compressed by the intestine and its contents, he could not cer-
tainly perform with the requisite deliberation this important act:
but the anus is in fact closed, rather than opened, by any irrita-
tion externally applied. The Fly would be crushed in attempting
to pass the sphincter of a horse's rectum ; and having no means
of holding while depositing its eggs, it would be quickly evacu-
ated with the dung ; and it is evident that the whole of the ova, '
to the amount of two or three hundred, must be deposited in
one horse, as it is impossible, if the Fly survived, that it could
undergo this punishment a second time, for the heat and mois-
ture of the rectum would at least destroy its wings, and prevent
it from attaining this situation.

I mention these objections, not as merely relating to this spe-
cies, but that it may not be credited of the (E. Nasaiis, or indeed
of any of them, that they really enter the body of the animal to
obtain for their young a situation there.*

# The fly D^f- Gaspari saw _was without doubt the Hippolosca Equina, or Forest
Fly from the circumstance of its getting beneath the tail, which this Fly often does,
and all the rest of the account was. added from imagination. That a fly might
deposit its eggs on the verge of the anus, is not impossible ; but we know of no
example or instance of it at present.

On dissection this Larva is found to possess similar air tubes
and alimentary canal. When it is ripe, and has passed through
the intestines, its skin becomes of a greenish-red hue. It gene-
rally assumes the Chrysalis state in about two days after leaving
the rectum, and is then of a deep-red colour.�See fig. 19-

The Larva of this species may be obtained from* almost any
Horse that has been much the preceding year at grass, and ex-
posed to these Flies, and will be found during the summer months
sticking more or less within the verge or opening of the anus,
adhering to its soft lining, and producing considerable irritation
and uneasiness. Indeed I once well remember being on a tour
of pleasure in the Isle of Wight, and experiencing much annoy-
ance from these larvas. The little Horse I had hired for the jour-
ney became so lazy and unwilling to go on, and moved so awk-
wardly, that I could not keep pace with my company, and I was
at a loss how to proceed ; but on casually taking up the tail, I
discovered three or four of these Insects hanging: to the rectum,
and their removal instantly proved a cure.*

When they are taken away from these parts with a view of
obtaining the Fly from them, it should be done with care, and
by a light sudden twitch or jerk of the fingers, not compressing
them ; for if squeezed much in this tender state, (for all Insects
are very much so when about to change to Chrysalis,) the Fly is
damaged, if not killed : in which case, though they undergo their
change to the Chrysalis, it never hatches.

From the beginning of June to the end of July or August,
they are found hanging in this way to the end of the rectum, as
though reluctant to leave their warm habitation. They appear
never to change their skin during their growth, as many other

* Vegetius observes, Cossi et lumbrici qu& curd- tollantur ad manum- Diligenter
tentabis et invenies vermes collectos exisse in singulis locis et intestinum pertundere
ex qua necessitate nascitur dolor periculosus. Digitis evelle eos qui quidem vix evel-
luntur et ipsa tibi in mauu cohaerent, ut difficile eos projicias. Lib. I. cap. 52.

Larvae ; if they did, it is probable they would lose their hold, as
the hooks are principally connected with the skin, and separate
with it by maceration, leaving an indentation where they were
lodged.

These Larva? have the power, when compressed or squeezed,
of contracting and hardening themselves, and it is probable they
in this way resist the violent pressure they must occasionally
sustain, from the weight of the food and the actions of the
stomach, and in passing through the intestines and the sphincter
ani.

After remaining in the chrysalis state about two months, the
Fly appears.�See fig. 12 and 13,�the male and female,�and
their description in the sequel of the paper.

This species may still retain the name of Hasmorrhoidalis, with-
out any impropriety, not from the supposed history of its enter-
ing the anus, but from the termination of the abdomen being
red, Linnaeus having generally chosen to distinguish the insects
so marked by that name ; also from their resembling the haemor-
rhoids or piles, while hanging to the extremity of the rectum.

The learned Charlton, (Onomasticon Zoicon, p. 56,) and after-
wards Dr. Johnson, (see Dictionary,) have considered ascarides as
the synonymous term among the ancients for the Bots : that term
has ever been applied to the thin smooth worms of the intestines,
but, I apprehend, never to these.

On the Oestrus Veterinus, or Red Bot.

The mode of this insect depositing its eggs or nits, is at pre-
sent unknown. By watching for them on the commons in the
warm days of the sixth and seventh month, (or July and August,),
it might be detected, I apprehend, without very great difficulty.
They perhaps deposit them about the lips or legs, as the former
species. The Larva of this species is also not certainly known.

That it inhabits the stomach as the two former species there is
little doubt; and I have taken considerable pains to search for it
at the slaughter-houses, and have found a species in the stomach
which widely differs from the Equi and Haemorrhoidalis, and which
I presume may be the Larva of this. I have given a figure of it
at PI. I. fig. 24 ; though it is possible there may be a fourth spe-
cies inhabiting the stomach of the Horse, in which case it may
be still doubtful, that I do not positively assert it to be this
Larva belonging to the Veterinus.

This Larva, if it is the Veterinus, may be known from the
two preceding species, being smaller, of a more tapering or
oblong figure, and the segments more detached and rounded,
shining, smooth, and of a pellucid red or ruby colour, more par-
ticularly at the tail or obtuse end. Although its coat appears
smooth to the naked eye, the microscope detects small spines or
points in double rows, the two lines alternating ; and these points
occur less frequently in approaching the large end, the two last
segments being destitute of them. In its very young state there
appears to be but a single row of these points, the second row,
or that nearest to the middle of the segment being wanting.
Two short vesicular palpi appear at the very extremity of the
large end, situated upon the lips which cover the air plate.

Through the thin transparent skin of this Larva when very
young may be seen the beautiful silvery tubes of respiration,
with their numerous ramifications, diverging, closing, bending,
and playing among the soft matters within, and accommodating
themselves to every movement of the animal.

I have also seen, as I apprehend, another species in the stomach,
which I take to be different to any of the before enumerated spe-
cies, and which is much whiter than the three preceding, being
almost perfectly white. I found them forming a cluster in the
stomach of a Horse early in the sixth month, or June, and there-
fore presume they were near their full growth ; their whiteness

was opake or milky, with hardly any redness about them, though
the last segment was somewhat faintly tinged with red. But
there appears in the spines or bristles a peculiarly distinctive cha-
racter, for they are in a single row only, and regularly placed in
a line, and the microscope could hardly discover that their points
were black, being minutely so, and hardly visible to the naked
eye, while the other species were distinctly so to some distance,
in make and other circumstances they resembled the Equi, but
were not above half their size. Having stated these circum-
stances, I leave the further investigation of them to the curious.

The real Chrysalis of Veterinus I once found in the neighbour-
hood of Worcester, in a meadow below Perry Wood, between it
and the city, under some horse dung ; and the figure of it was,
as near as I can remember, for I threw it away after the Fly came
out, much like figure 26, which is done from memory, for at
that time I had no prospect of ever having to write on these
subjects.

This Fly, after it left the Chrysalis, being confined under a
glass in my window, became, if I remember right, singularly
active and impatient, and destroyed in its rage one of its wings,
drawing it towards its mouth with its legs, and devouring it, as
it appeared, and whirling round with considerable velocity and
noise upon its back. Whether other flies so confined would do
the same I know not.

I think Reaumur's figures I have referred to are certainly meant
for this species, but the figures 1 and 2 are evidently two differ-
ent Chrysalides, though given for the same. The one is of Has-
morrhoidalis or Equi, the other smoother, and probably of this
species. Tom. IV. pi. 35. The Larva of this species is not given
by him at all, but in the preceding plate there is a good figure of
the Larva of the Hasmorrhoidalis, which he considered the same,
and the Flies 9 and 10 are the Hasmorrhoidalis, though badly
executed. As far as I remember, the Fly of Veterinus, in making

its way out of the case of the Chrysalis, broke away the three or
four last segments of the small end, leaving a ragged edge to the
opening, but not a regular marginated operculum as given in
Reaumur's figure, and which operculum is so remarkable in the
Chrysalis of the Oestrus Bovis.

This Insect proved a male, fig. 26 ; and I afterwards in the
cabinet of Linna3us, obligingly presented to my observation by
Sir James Edward Smith, found the female, fig. 27, with a short
stylus to the abdomen. Some other specimens of this species
were found in this cabinet, taken from the collection of Hudson,
the ingenious author of the Flora Anglica, nearly spoiled, and
entangled in the melted wax with which his drawers were covered,
as was the custom of those days before the use of cork. A misera-
ble fire consumed his house, and nearly his Herbarium, and occa-
sioned the melting of the wax before mentioned.

Linnaeus supposed this Insect entered by the nostrils and lived
there as the other did by the fundament ; but as no insect would
destroy its own wings, and so miserably punish itself, we have
ventured to obliterate the name, that erroneous notions should
not be suggested by it.�For its description see the conclusion
of this dissertation.

It appears to me that more certain information might be ob-
tained respecting this and the other species that infest the domestic
animals, by a very simple method, and which I propose next year
to endeavour to prosecute, if my health and present views re-
main. For this end I propose to procure from the slaughter-
houses, and the stomachs of dead horses there, such of these ob-
scure species in the Larva state as it may be desirable to investi-
gate ; and since they cannot be fed with any prospect of success
out of the body, I intend to inclose them in a ball of meal, and
administer them to my own horse, as balls of physic are admini-
stered, and in his stomach they will perfect their growth. I next
intend to have a stall boarded at bottom and closely jointed, with

a margin round to prevent the escape of the Larva on its falling
from the intestines ; or indeed, and which would be better, a
small apartment entirely constructed for this purpose, of dimen-
sions that would give the horse his liberty, and where he is
intended to be chiefly kept during the two or three months of
summer. On this floor might the Larva?, by examining the dung
two or three times a day, be collected, and thus fully grown
Larva? being obtained, there would be no difficulty in raising them
to the state of a Fly by keeping them in boxes filled with earth,
or a mixture of dung and earth, till the Fly appeared. In this
way what is unknown of their sexes, species, and history, might
be correctly made out, and further on the Fly coming forth,
if confined in a suitable apartment, they might even be presented
to the Horse, and the mode of depositing their eggs be seen,
their copulation having been first permitted, which Vallisneri
informs us they are not shy in performing coram teste,

I am induced to notice in this place a Fly belonging to this
genus, a figure of which is given at No. 28, and whose history we
are at present quite unacquainted with. I obtained it, with some
other Insects in the sale of Drury's collection, about ten years
ago, and by way of distinguishing it till its history becomes known,
shall bestow on it the name of Oestrus Microcephalus. It may be
the Oe. Trompe or Pecorum of Fabricius, or both.�See the
description at the conclusion of this essay. Its general appear-
ance, and the distribution of the tendons of the wing, would lead
me to refer it to the Cuticular Oestri.

Another species also, whose history we are at present in the
dark about, is given at No. 30, which I formerly placed under
Hctmorrhoidalis as a variety f3, but observed that it differed from
it in the essential circumstance of having a large white wing-
scale : (3 variat squama halterum majori lactea magna ac facie
magis depressa. Lin. Soc. Trans. Vol. III. p. 328. It has since
been taken on the heaths near Plymouth by Dr. Leach, who has

named it Oe. Ericeiorum, but now conjectures it is no other than
the male of the Oestrus Bovis.

Its face strongly resembles that of an ape, and the remark in
my dissertation above quoted was made from observing this spe-
cies. " From etiam quadrupedis nonnihil simulat, presertim simict :
hoc in Oe. Hxmorrhoiduli tnaxime conspicuum est" &c. Lin. Soc.
Tr. 3. p. 325. The hairs in the upper part of the face also form
an arched projection not very unlike the projection of the skull
of the monkey over the orbits of the eyes, and the black an-
tennae sunk in the head, have much the appearance of eyes.�See
fig. 32.

On the probable Effects of the Gastric Oestri upon Animals.

Unacquainted with their history, the appearance of inhabi-
tants like these in the living stomach, would, to superstitious
people, or even in strong minds, produce apprehensions of their
pernicious or fatal effects, especially when they saw the coats of
the stomach eroded as it were in holes nearly through by them ;
yet but few horses exposed on the commons can escape having
them, and the perfect health they enjoy with them is a proof
sufficient of their innocuous nature and harmlessness in a general
way.

That the coats of the stomach are not particularly irritable to
mechanical stimuli, is proved from daily experience by offences
committed against them. Some kind of fishes have their sto-
machs completely perforated through by the bones of the fishes
they feed upon, without any derangement of their health, or
probably much sensation ; and the white tissue of the Horse's
maw is certainly less sensible than the other parts of the stomach,
that it is fair to conclude our apprehensions of their effects have
been carried much too far: if the tone of the stomach should be
changed by inflammation or other disease, their roughness might

perhaps become then very sensibly felt, and their powers be
changed. That they contribute to health in some degree is, I
think, very probable, for notwithstanding the apparently un-
necessary existence and cruel effects of the Oestri, they are pro-
bably not altogether without an use, and were not designed by
Providence to add, without a recompense, to the numerous suf-
ferings of these useful and laborious creatures.

A physiological view of their effects will, perhaps, best justify
their existence, and save them from such an imputation.

To see the full purpose of their existence may not be within
our power in our present state of knowledge, yet we nevertheless
may introduce some remarks in this respect as a foundation, and
whether a permanent one or otherwise, we shall not be tenacious
about ; they may, at least, lead to further consideration and
research concerning them.

Throughout nature the benevolent design appears of leaving
no place idle or unoccupied, that can conveniently or usefully
afford a home and happiness to some being suited to it, and which
sometimes, in its turn, may also be made to contribute to the
welfare of the animal it is given to infest.

These parasite animals, though uncouth and almost of them-
selves a disease, may prevent the access of worse diseases, and
in such situations as would produce them of a fatal nature, and
prevent it by their local effects. Children of cachectic habits
breed worms faster than healthy children, which may tend to
suppress or moderate the disease they incline to ; and sheep, in
low damp situations, which might produce a worse disease, be-
come in these situations particularly infested with these parasitic
animals. Linnaeus, in respect to Pediculi or Lice, has admirably
observed, " Rodendo caput exciatachores apud puerulos voruces in-
carcerates indeque strumosos et sicque preservat a coryzd, tussi, cceci-
tate, epilepsia," &c. That is, that Lice, by gnawing or irritating
the .skin of the head, excites a sort of running sores amongst boys

kept in filthy workhouses, or confined places, and become strumous
or swoln by the confinement, by this excitement are preserved

from coughs, wheezings, blindness, epilepsy, &c.------In more

cleanly situations they would not be subject to one, nor then
would they be so obnoxious to the other, or in any consi-
derable degree however. Some constitutions, inveterately sub-
ject to the morbus pediculosus, would perhaps serve to confirm this
remark ; also by their having a strong tendency to some disease
which these animals may tend to avert, and in which constitu-
tions the facility of their propagation becomes in a wonderful
manner increased so as to almost defy their eradication, which in
stronger constitutions, and free from disposition to disorder,
would not be the case. These Gastric Oestri, perhaps, in a state
of health, without producing the terrible consequences usually
apprehended, may tend to preserve it by their gentle stimulus to
the stomach, and by promoting the digestion of their low watery
food, prevent the cholic, gripes, and other indigestions which
ultimately affect the head of the Horse, and producing staggers,
a disease the horse is particularly subject to.

Nor is there Avanting abundant proof of the utility of local
irritations in preventing the access, as well as in curing disorders.
We often see a formidable disease quickly removed by blistering
the skin, or by irritating the mucous membrane of the stomach
or intestines by a vomit or purge. The appearance of exanthe-
matous eruptions on the skin, and the formation of local abscesses,
from the same cause of partial irritation, often relieve a general
disorder of the system. The mucous membranes and the skin
possess this power when irritated in the most eminent degree,
and to these the Larvse of the Oestri are applied. Irritating the
membranes of the stomach in other animals would excite nausea
and vomiting ; but the Horse not possessing this power, his sto-
mach is peculiarly fitted for the stimulus of such inhabitants.

It has also been remarked in hospitals, that a patient afflicted

with a wound, ulcer, or other severe local complaint, is not so
susceptible as others similarly exposed to the contagion of a fever
or other general disorder.

How far the access of those dreadful disorders which some-
times arise of themselves in cattle and horses, and afterwards be-
come contagious, as the murrain, glanders, farcy, &c. may be
prevented by these peculiar irritations, it will not be easy to dis-
cover ; nor whether that singular tendency or disposition in the
Horse to inflammatory complaints, as the caligo of the eyes,
termed moon-blindness, inflammations of the lun^s and of the
bones, as spavins, splints, &c. may be in any degree checked or
subdued by the presence of these local stimuli.

In confirmation of this suggestion I may remark (although I
am aware other reasons may be also assigned for it,) that those
Horses which are not exposed to the Bots, more frequently are
infected with the glanders, farcy, &c. as those of the army, post-
coaches, post-waggons, and dray-horses, for these can rarely be
spared, from the nature of their work, to graze on the commons,
and thus be exposed to receive them.

If, after a more minute research into their effects on the system,
the utility of these native stimuli of animals should be established,
and, like the leech, or the cantharides, they should be called in
to the aid of veterinary medicine, I may venture perhaps for the
first time to suggest that it would not be impracticable to admi-
nister them artificially by means of their ova or larvse in any
given quantity.

If the stimulus is considered as of too gentle a nature, it is in
some measure atoned for by its permanency, and the unlimited
power of increasing the dose ; at least it must be acknowledged
that by the administration of them in this way, we might accu-
rately ascertain their real effects, and whether they are so fatal as
has been imagined.

Desirous that my horse, which had not been to grass for some

years, should have their wholesome stimulus, I cut off the hairs
from another horse charged with the Bot's eggs, and gave him
about three dozen of them. He afterwards grew fatter, and in
better condition than I had ever known him, whether from their
effects or not I do not undertake to determine, but think it not
improbable they contributed to it.

In Nasal Farcy Gleets of Horses, I have followed this sugges-
tion of stimulating the stomach by Cantharides in small doses,
and by the Sulphat of Zinc, with great success, curing several
that were considered g'andered.

The domestic animals in a particular manner appear to be the
objects of this species of natural stimuli or vellicatories, which
as they are also frequently forced by man into unnatural exer-
tions and unhealthy situations to suit his views and convenience,
so therefore they may stand more in need of this sort of protec-
tion. Their impressions may be hardly cognizable to the senses,
and produce nevertheless powerful effects upon the stomach, and
thence to the system at large, as we see in the case of spices
given with food, and fomentations, mild blisters and sinapisms to
the skin.

How dirty in warm climates would men become, if it was not
for the fear of the increase of vermin, that they can stimulate to
industry therefore is certain, and so to health. Animals would
become inactive in warm weather, perhaps fatally so, if it was
not for the stimulus of flies and other insects, which by teazing
prevent it.

Those who consider the Bots as a plague would no doubt be
desirous of being informed how they should best destroy them.
One great utility in the study of natural history is, that it affords
us a knowledge of the habits of these animals, and by these we
are taught the most effectual measures for this purpose. It is
indeed truly difficult to detach them from the stomach by any
medicines or poisons administered internally, though there are not

wanting abundant nostrums for this purpose among the numerous
professors of horse physic. At the natural annual period of their
transformation they come away readily enough of themselves ;
and if it happens at the time that any medicine has been exhibited,
it is considered as proof enough of its efficacy, and mistaken for
the consequence of it ; so easy is it to draw wrong conclusions.
Neither opium or tobacco given for several days have any effect
upon them, as I have witnessed by opening the stomach after the
death of such, and finding them lively and well. We can, it is
true, force the poison down the horse's throat, but we cannot
afterwards get it into the throat of the worm, who is placed in his
own element, and can refuse the food that does not suit him.
Truly is it therefore difficult to destroy them by means of poisons
thrown into the stomach.

Oils; to close the pores of respiration, and thus kill them, was
a favourite suggestion of the last age for worms of all kinds, and
it was thought must infallibly kill them : nevertheless it did not.
These oils probably in the stomach are soon reduced to a soap,
and digested ; how much less then could it affect worms situated
in the intestines.

The wisest measure for securing animals from their effects is to
prevent their propagation or access, and their habits expose to us
an effectual mode of doing this. The eggs of the Oestrus Equi,
which are very conspicuous on the knee, the mane, and the sides
of the horse, may be washed off by a brush and warm water, or
still more effectually removed by a pair of scissars. The same
may be done for the Hgemorrhoidalis from the lips and beard.

The other species being smaller, more rare, and probably less
troublesome, require therefore less our consideration.

In respect to the Haemorrhoidalis also, where horses have been
much out at grass the preceding year, they should occasionally in
the warm months of the next summer be examined for them, when
they will be found, as we have already stated, hanging to the

extremity of the rectum, and should be removed by the fingers.
The destruction of a single one at this season of the year is not
only the death of an individual and its effects, but the almost
certain destruction of a numerous progeny ; it is also useful in
preventing the irritation which the spines of the Bot occasion to
the anus, which irritation becomes very distressing to the ani-
mal if he is used on the road, occasions him to move awkwardly,
wriggle himself about, and to be sluggish, and though beaten
severely he soon relapses again into his awkward manner of going ;
which as this happens generally in warm weather, is most com-
monly attributed to mere laziness.

Some further remarks on their probable effects we leave till we
treat of the Cuticolar and Cavicolar Oestri.

* * Second Family, CuticoLjE.

The Oestrus Bovis, or Gad Fly.

Of all the European species of this genus, this is the largest,
and is not unfrequently seen in country situations in the backs of
oxen and cows. They form tumors as large as pullets eggs on
the sides, about the back and loins. See their appearance, Plate
II. fig. 2, a the tumor or abscess, b the external opening. With
us among the country people they are called Warbles, Wornils,
Wormuls, and sometimes Bots.

When I first took up the investigation of these animals, I was
in considerable perplexity what this species could be, since I
possessed the Oestrus Bovis of Linnaeus, agreeing perfectly with
the description, and which was a Horse Bot ; nor had I then
seen the writings of Vallisneri or Reaumur, which, as Linnaeus
had seen and referred to, I did not suppose could have fallen into
such an error as to have omitted entirely this remarkable species,
or have confounded it with the Equi, but it so proved, and on
obtaining the perfect insect from the back of the cow, the mys-

♦

tery became unravelled; for I was not certain, indeed apprehended
after such authority, that the same species inhabited both animals
as Linnaeus had stated, " Habitat intra Boum dorsum, in ventr-i-
culo Equorum saepe ipsis lethalis." Lin. Syst. Nat. p. 969. This
insect was not known to Linnaeus, and, indeed, has been rarely
seen; Vallisneri, after years of labour, procured only one muti-
lated specimen of it; and Reaumur, after great pains and expence,
only two or three. A mode of obtaining this fly, which suc-
ceeded with me perfectly well, I shall now describe, by which I
obtained out of three larvae two perfect flies, one so perfect, that
it flew away while I was making some experiments in presenting
it with different objects; the other I gave to Thomas Allen, Esq.
after drawings had been made from it for the use of the Linnaean
Society. One I also fortunately caught of these flies, between
Salanche and Bonneville, in Savoy, flying in the road, and settling
on some dung where cattle had recently passed ; this specimen,
on my return through Germany, I presented to the venerable and
worthy Professor Daniel Schreber, of Erlang, the intimate friend
and pupil of Linnaeus, who till then had not seen it.

The following is the simple means for obtaining them perfect,
which may be not unacceptable to those who for their cabinets or
from curiosity may Avish to see them :

Daring the latter months of the summer, about which time
the larvae are found fully grown, and about to quit their habita-
tions, which can be known by the superior size of the abscess,
and especially the increased diameter of the external opening ;
such being selected for the experiment, we remove the hairs
round the tumor to a considerable distance with a pair of scissars
as close to the skin as may be ; and a piece of leather, thickly
spread with pitch, being provided, through the center of which a
hole is cut about the size of the finger, and into this a small
gauze pouch or bag is inserted, hanging out an inch or two from
the leather: this plaister with its pouch is then placed upon the

skin, to which from its warmth, which is very considerable, it
readily adheres, the pouch being opposite the opening. When-
ever the insect makes its way out and falls from the abscess it is
caught by the bag, in which, as it cannot escape, it remains till
removed by the person looking after them. The larva thus
obtained, as it is full fed, will hardly fail to produce a perfect fly ;
it is only necessary to put it into a pot with some loose light
earth for it to change upon.

That we may continue the history of these flies with some
degree of uniformity, we shall commence its operations with
some remarks on the deposition of the eggs, as we have done
with the former species. This act appears to be attended with
severe suffering or apprehension at least, which makes the cattle
run wild and furious and gad or stray from the pastures ; and
hence the ancient epithet of Gad-Fly. When yoked to the
plough, the attack of this Fly is attended with real danger, since
they become perfectly uncontroulable, and will often run directly
forwards through the hedges, or whatever obstructs their way.
There is provided on this account, to many ploughs a contriv-
ance immediately to set them at liberty. When the cattle are
attacked by this Fly it is easily known by the extreme terror and
agitation of the whole herd; the unfortunate object of the
attack runs bellowing from among them to some distant part of
the heath or the nearest water ; the tail, from the severity of the
pain, is held with a tremulous motion straight from the body, and
the head and neck stretched out to the utmost. The rest from
fear generally follow to the water, or disperse to different parts of
the field. See Plate II. fig. 1.

And such is the dread and apprehension in the cattle of this
Fly, that I have seen one of them meet the herd when almost
driven home, and turn them back, regardless of the stones, sticks,
and noise of their drivers ; nor could they be stopped till they
reached their accustomed retreat in the water.

The strongest and healthiest beasts seem to be preferred by
this Fly ; and* with the dealers in cattle their possessing them is
held a criterion of goodness. The tanners, also, observe their
best and stoutest hides have the greatest number of Bot-holes in
them.

It is not yet satisfactorily ascertained, whether this alarm is the
effect of an instinctive fear of the Oestrus ; or whether, in depo-
siting the egg they inflict a painful wound ; or if there is a sound
given by the Fly which is frightful to them. The scale at the
base of the wings of this Fly is remarkably large ; and this part
has been supposed by Keller, and other writers on this subject,
to be the organ of the sound or buzzing we hear from these ani-
mals. This magnitude of the wing-scale would favour the opi-
nion of Virgil of their attack being accompanied with a noise
" asper, acerba, sonans," &c. Those, however, I saw in flight
made not the least sound that I could perceive ; still it may be
true, that in the act of inserting the eggs, from certain feelings or
emotions accompanying this act they may be led to do so. In
the Rhein-deer Gad-Fly Linnaeus saw the egg protruded and
held out upon the point of the abdomen, like a white seed, ready
to be placed upon the skin of the animal; he makes no mention
of any sound accompanying it in this Fly, and this circum-
stance of the protrusion of the egg would lead us to infer, that
no wound is inflicted by the Fly, whose tail, like the tube of a
telescope, piece within piece, appears of a nature no way calcu-
lated for such infliction. The Ichneumon Fly, we know, deposits
its egg upon the naked skin of the caterpillar, whicli egg adheres
strongly to the skin, as though glued to it; and the little grub,
on the hatching of the egg, makes its way through the skin into
the body of the caterpillar, and there feeds till ripe ; and it is
equally possible, that the skin of the ox is perforated by degrees
by the young larva of the Gad-Fly, till it obtains its situation
beneath the hide. The animal is so frighted that it has not the

power of lashing them off with the tail. Sometimes horses, also,
are attacked by the Gad-Fly, and I have been witness to four or
five instances of these larvae being found beneath the skin of the
horse, the parent Fly, driven perhaps by necessity and the want
of proper opportunity of depositing it among the cattle : whe-
ther they ever arrive at maturity in these cases I am not assured.

The larvae of the Cuticolar Oestri are very unlike the Gastric
larvae, so much so, that I could hardly imagine that they would
produce an Oestrus till I actually procured the Fly from it.

Removed from the abscess this larva is found of an oblonc
figure, larger at one extremity than the other, which larger end is
placed upwards in the abscess, has the respiratory plate, and is
applied to the external opening of the abscess. The body of the
larva is divided into ten or eleven segments or sacculi by trans-
verse bands ; these are crossed again or intersected on the sides
by six longitudinal lines, pursing up the skin, and forming the
sides of the larva? into so many papillae or nipples, each possess-
ing at its extremity a respiratory pore. See Plate II. fig. 3.
These larvae have not the long acuia upon the edges of the
segments, as in the Horse-Bot; but they have an apparatus
which serves much the same purpose, but in a milder degree, for
there are observable on a more close inspection, ridges of dotted
prominent lines passing transversely round the body of each seg-
ment, and interrupted irregularly by the longitudinal lines above
described, leaving smooth intervals between them : of these
there are two kinds, a narrower and a broader line of minute dots
or points ; the first, or narrower line, is easily seen by using a
lens to be formed of hooks bent upwards or towards the tail of
the insect. See fig. 3. a. And on examining the broader lines,
consisting of smaller dots, fig. 3. b. with a powerful magnifier,
they also may be seen to consist of hooks, but smaller, and
turned in the opposite direction, or downwards in the abscess^
and towards the head of the insect, It is probable, by means of

these hooks, erected by the muscles of the skin, the animal raises
or depresses himself at pleasure, or turns about in the abscess and
finally crawls out of it when ripe. The use of the terminal ten-
tacula, observable in the Gastric species, would have been useless
in this, as the oval form of the abscess retains them in their
abode sufficiently secure. And b_y the motion of the larva in the
abscess these hooks, by irritating the surface of the sac, produce a
discharge of pus for sustenance.

In what manner the nourishment is received by this larva is
not immediately discoverable. Indeed, it was not known to me
till an unexpected circumstance led me to its discovery ■ on im-
mersing one of these larva? in warm water with a view to rid it of
pus and slime, I observed a considerable quantity of pus to
be ejected from an aperture, which at other times was closed,
this was at first considered to be the mouth; it, however, was
found on further research to be the real anus of the larva, for it is
in the upper part of the larva, or that end which is applied to the
external opening in the skin, (where may be also observed two
small horny plates,) which are found on dissection to close the ex-
tremities of the trunks of two large air vessels. Near to these plates,
and somewhat above them, this minute puncture is discernible.
At other times, when closed, it was discernible with the utmost
difficulty. At fig. 3. is represented this aperture, a. together with
the two horny plates, which close up the air vessels, being a view,
very considerably magnified, of this upper extremity of the
larva.

From a first view, this part would appear to be the head of the
larva, being uppermost in the abscess; but as it is found to pro-
duce the extremity of the abdomen in the future insect, it must,
therefore, be considered as the tail; and the above-mentioned
minute aperture is undoubtedly the anus, and is found to be in
conformity to the same situation of the anus in others of this

genus. And this would seem to render it manifest, that through
these plates they receive the air, and emit it by the spiracula.

At the lower end of the larva, fig. 3. a small indentation may,
with attention, be observed, which is the mouth of the larva. It
is a simple aperture, and altogether unprovided with any of the
apparatus belonging to the mouths of larvae in general; and near
the mouth are seen two black points of horn, which appear to be
perforated in the centre, and are found by dissection to be the
termination of two considerable branches of the air tubes, and
correspond to the two nipples on the first segment of the larva of
the QE. Equi. An enlarged view of the mouth and inferior part
of the larva of the QE. Bovis is seen in fig. 4. Round the orifice
of the mouth are placed some projecting mamilla?, which are
imperforate, and perhaps serve the purpose of feelers.

The intestinal canal in this larva is a simple membranous tube,
which extends from one extremity to the other, and serves the
double purpose of stomach and intestine.

In the larva of the Oestrus Bovis there are only two principal
trunks of air vessels, which are connected near their origin by a
lateral trunk. From these trunks branches are seen passing in
every direction through the parenchyma or matter of the body
of the insect, some going to the intestine, others to the skin, and
a greater number appear to be forming an anastomosis with each
other.

When young the larva is smooth, white, and transparent ; as
it enlarges it becomes browner ; and about the time it is full
grown it is totally of a deep brown colour.

The larva having attained its full growth and size, effects its
escape from the abscess by pressing against the external opening,
which occasions its enlargement by the points pressed upon being-
absorbed, and the skin also may give way and extend itself under-
their impression. When the opening has obtained the size of a

small pea, the larva writhes itself through, a ring or segment at a
time, till arriving at the narrower part of its body it falls out,
and tumbles to the ground, and seeking a convenient retreat be-
comes a chrysalis.

After leaving the abscess, and preceding their change, they
contract themselves into a much smaller spade, and assume a dif-
ferent figure. See Plate II. fig. 4. They never change or throw
off their skin, apparently, but the same serves them through their
whole growth, and at length also forms the shell of the chrysalis,
as in the other species of this genus.

If we examine the sac which enclosed the larva beneath the
skin, it appears formed of condensed cellular membrane, and is
rough on the inside. The pus secreted is mostly of a yellow
colour, and sometimes flows from the opening, and dries about
the orifice. After the exit of the caterpillar the abscess disap-
pears, and the wound in the skin closes up and is healed in a few
days : but although the skin heals up on the exit of the larva, we
may remark, that the union is not so firm as was the original
skin, but is affected by a sort of agglutinating deposit, which
afterwards on the skin being dried and hammered by the tanners
gives way and cracks again in these places, shewing the union to
have been of a less perfect nature than the original skin ; the
succedaneous nature of the repair of broken skin, has been
remarked by late physiologists, and we mention this fact as con-
firmatory of their doctrine.

The chrysalis is of a dark brown colour, and in figure some-
what resembles the half of a walnut shell, being narrower at one
end than the other, and fiat on one side, and very rounded and
convex on the other. See fig. 6. Those which I bred remained
in the state of chrysalis from the latter end of June till about the
middle of August, when the Fly appeared. I have, notwith-
standing, observed full grown larvae in the backs of cows as late

as the ninth month, or September, which must have produced
their Flies as late as November or December, or perhaps not till
the ensuing summer.

The larva after being immured in the chrysalis a sufficient
time, and its soft members dry and in a degree hardened, bursts
from its confinement by forcing open a very remarkable triangu-
lar lid or operculum, see Plate II. fig. 7- and makes its way out at
the small end, a. The position and appearance this Fly makes in
the chrysalis is also given.

The larva at the period of making its way from the back of
the beast is weak and tender, and exposed to imminent danger,
if on land, of being trod on by the cattle or picked up by birds;
if on the water, where the cattle stand during great part of the
day at this hot season of the year, it perishes by drowning or
becomes the food of fishes.

It is worthy of remark, that Reaumur has stated that its escape
from the back of the beast usually takes places at a very early
hour of the morning, at two or three o'clock, or at sun-rise, now
if it be so it is remarkable that in this way much of the danger is
avoided, as the animals at this time would most probably be
upon dry land, and in a more quiet state than at mid-day, and
the birds also would not then be present.

The Fly thus singularly produced, is large and handsomely
coloured, see fig. 8. and 9- Plate II. and its description at the
conclusion of this Essay ; its wings and tendons, fig. 10. and the
abdominal stylus of the female for depositing the eggs, according
to Reaumur's drawing, fig. 11. To the extremity of the abdo-
men of a specimen of the Oestrus Bovis which I possess, there
is something visible like a hard white stylus, or rather spine, of
whose nature I am not assured.

As to their effects, they may be perhaps not inaptly considered
as the living rowels of the ox, producing in all respects the same

effects as an artificial inserted rowel, issue, or seton, would do;
and these perhaps first suggested in ancient times to practitioners
in medicine these very useful remedies.

The cattle are subject at times to violent cephalic disorders
and epidemics, especially in the warmer climates, which these na-
tural cutaneous irritants or suppositories, as they may be called,
may tend to avert; and they may operate in a more forcible and
determinate way, in producing all the effects of the Gastricolar
Oestri, already noticed, the skin having such a general sympathy.

In respect to the riddance of them where they may be con-
ceived mischievous, we may observe, that the larva of the
Oestrus Bovis, which breeds in the backs of horned cattle, is so
conspicuous, that it is more easily destroyed than the others: the
injection of any corrosive liquor into the sinus would kill it; or
by punctviring the larvae with a hot needle, introduced through
the apertures in the skin, or even by simple pressure, they may
be destroyed, afterwards extracting them, or leaving them to
slough away, which I have frequently observed they do when
crushed by a blow from the horn of the beast, or by any other
accident, without any material injury to the animal. A man em-
ployed for this purpose might, in half a day, in this manner
destroy every bot on a large common, the beasts being suffered to
pass one at a time in review before him.

Of the Oestrus Tarandi, or Rhein-deer Gad-Fly.

The Rhein-deer delights in the cold of the north, and appears
destined most beautifully to fulfil by himself to the polar inhabitant
the various offices of the horse, cow, and sheep, of the more south-
ern regions, carrying burdens, giving milk, and affording clothing :
and this worthy animal appears in a remarkable manner to suffer
from the effects of the Oestrus, with which he is infested, more
than the other domesticated animals, so much so, as to occasion

the Laplander to quit his abode several months of the year, and
oblige him to go with his Rheins into the Upland Alps, in order
to avoid their effects. The gnats or musquitoes also, in these
regions are more troublesome than in any other part of the world;
so that not only the rigours of the climate, the unproductiveness
of the earth, and the hard condition of life, but the very insects
appear to contribute to drive men from these situations into more
hospitable latitudes.

The Rhein-deer Bot had attracted very little notice till the
writings of Linnaeus presented many interesting details respecting
them to the lovers of natural history; and from his various scat-
tered notices or memoirs we have extracted the following details :

In the Flora Lapponica, p. 360, in describing the Agarics and
Lichens of this part of the world, he introduces his remarks on
the Rhein-deer Gad-Fly ; as the Rhein-deer is chiefly fed during
the winter on one of these, the Lichen rangiferinus, which is very
abundant in the north, as though provided for them, and is serv-
ing perhaps in some instances also, as a covering from the incle-
mency of the weather to vegetables.

He afterwards in a sort of journal of his tour, written in Swe-
dish in the Acta Stockholmia for 173.9, p. 119, gives further parti-
culars of their history. And in the Acta Upsaiiensia, 1736, p. 102,
he enters again on this subject with some variations.

Their depredations he describes as most bitterly felt by the
inhabitants of these regions ; and after a few pious and admiring ■�
reflections on the ways of Providence in providing for these Flies
in their delicate and tender larva state, he observes, that in his
journey into Lapmark in the year 1732, he found all the inhabi-
tants had quitted their plains and woodlands for the hilly country
and Alps. One only he found dwelling there with his Rhein-deer
(Rheno), whose horns, soft, tender, and sore, were miserably
punctured by the Tabani till they distilled blood ; and that the
gnats also joined in the persecution with their little trunks con�

tinually infesting them. The animal, to avoid their effects, would
prostrate himself before the little hut of the Laplander, and be
secure from the teazing of his enemies by the smoke of the burnt
agaric, which proceeded from it.

On passing afterwards into the Lapland Alpine country, he ob-
served a Rhein-deer, loaded with his own pack, frequently to stop
short and become suddenly quiet and motionless as a pillar of
stone, or one struck with catalepsy, the head held out straight,
the ears upright, and eyes fixed; nor by any ill treatment could
he be induced to proceed, but in a little while he would again
resume his march.

Early one morning, while he was in bed between two skins of
the Rhein-deer, he perceived a very ungrateful stink, when day-
light, appeared there were standing about the cot a thousand of
these Rhein-deer, driven by old men, young, boys, dogs, and
women, who milked these animals. They appeared to be under
the apprehension of some invisible attack. The animals carried
their heads aloft, their ears pricked up and extended, beating the
ground and kicking in the air with their feet, as though by
enchantment; then for a while they would be quiet, then again
they were seen most furious, and this with so general and regular
a movement, that no army would have surpassed their exercises
in uniformity. On asking the Laplanders the cause, they told
him it was these Flies.

Anxious to ascertain the truth of this, he was able with nice
observation and scrutiny, to perceive flying backwards and for-
wards in the air some of these Flies, which he endeavoured to
catch, and assisted by the Laplanders succeeded in taking four or
five, which he sat down with pen and ink, greatly to the amuse-
ment of the Laplanders, to describe, which occupies the remain-
der of this pleasing essay, and which we shall give with the others
at the conclusion.

He observes, that those which he took had no weapon at the

extremity of the tail for inflicting a wound, nor was there in the
mouth any aculeus ; that their effects upon the Rhein-deer in so
driving them did not admit of explanation. He describes the
abdomen as having a telescopic tube at its extremity, which is
probably similar to the one already given with the CE. Bovis, and
is peculiar to the female, as in other Flies. On observing the
tumors in the back a few weeks afterwards, that had been touched
by the insect, he found an opening that would admit a goose quill;
he squeezed these tumors with his fingers, which the animal could
but badly endure, but he persisted in pressing them till he made
the larva come out through the opening, which he describes as
being white, of an oval figure, extremely tender and delicate, the
extremity black, which presented to the opening. The body with
circular folds and curved lines.

One of these flies he describes as following the rhein-deer that
carried his clothes, and was always near or upon the animal ; she
had her tail held out, and carried rather to one side and curved
upwards, and upon its extremity a white egg, as large as a cynips,
or hemp seed perhaps. I had (he says) an opportunity the whole
day of seeing this insect continually following him, and sometimes
going before him ; and so careful was it about depositing its egg,
that it did not care to place it upon the rein-deer if it did not
stand tolerably still, but dropped it on one side; and so persevering
was it to follow him, that at last it became exhausted and fainted
away, and fell down on the snow mountain with fatigue, so that it
could be taken with the hands, but shortly after, when it had been
a minute on the snow and recovered itself, it flew to the next green
spot, where it rested, and then again pursued the rhein-deer.

It was curious to observe the striving of the dogs, the boys,
and the rhein, which would run many times round the hut of the
Laplander, before it would proceed to the pasture where it was
to feed, if with the wind, but against the wind the rein would
proceed with alacrity, for by his flight when proceeding in this

.direction he could outstrip the fly which, forced back by the cur-
rent could not so easily follow him. At break of day, and in the
evening, it was curious to observe these conflicts. He observes
how admirable it is that these Insects are secured from the cold
by their provident Creator, by the dense warm covering, and
the thick matted long hairs of the Rhein-deer's back, and that
the back and not the sides is chosen for their nidus, otherwise the
animal by lying down would crush them. And the long hair of
these animals in summer, standing upright, and detached as it
were from the skin, enables the Fly to deposit her egg between,
on the more exposed and naked parts. And the times of their
formation in the backs is the time of the rhein-deer shedding his
horns ; and the stumps being then soft and tender, prevents his
destroying them. Linnasus also compares its effects to that of a
fontanelle or issue, formed by a pea in the human subject ; and
how wonderful, he observes, it is that so large an animal, which
might defy the strength of man, cannot nevertheless defend him-
self from, or resist the attacks of this small Fly.

He says that a third part of the rhein-deer, if I understand
him rightly, are destroyed by this fly, occasioning the disease the
Laplanders call Curbma, the name they give to this fly. Their
effects perhaps in this respect are exaggerated, and the deaths,
from whatever cause, too easily attributed to this troublesome
insect, as the death of horses has been too often to the Equi, by
the ignorant.

Some farther circumstances respecting them appear in the
Lachesis Lapponica, or Lapland Tour of Linnasus, the translation
of which from the Swedish has been lately published by Sir James
Edward Smith, Vol. II. p. 38 :�" These animals are sometimes
attacked with a vertigo or dizziness in the head, which causes
them to run round and round continually. The people assured
me, that such of them as run according to the course of the sun,
may be expected to get the better of the disorder; but those

which turn the contrary way being supposed incurable, are im-
mediately killed. The recovery of the former is thought to be
promoted by cutting their ears, so as to cause a great discharge of
blood.

" The Kurbma or ulceration caused by the Gadfly takes place
every spring, especially in the younger fawns. Such as are
brought forth in the summer season are free from this misfortune
in the ensuing spring ; but in the following one many of them
lose their lives by it. When come to their full size and strength,
the consequences are less fatal: but no rhein-deer is entirely ex-
empt from the attacks of this pernicious insect.

" Such of the male rhein-deer as are destined to serve for a
stock of provision are killed before the rutting time, and their
carcasses hung up, exposed to the air and frost before flaying.
The flesh is smoked, and a little salted, and then laid upon
sledges to dry in the sun, that it may keep through the winter
till spring. About the feast of St. Mathias (Feb. 24) the rhein-
deer begin to be so incommoded by the Gadfly, that they are not
in a fit condition to be slain for eating. From that period there-
fore, till the milking season, the Laplanders are obliged to live
on their stock of preserved meat. At other seasons of the year
the females are killed for immediate use, according as they are
wanted." Vol. II. p. 42.

Other particular's are also given in these volumes, but as they
were derived from the mistaken information of these untutored
people, I forbear their insertion; and Linnaeus himself had
omitted them in those communications quoted at the beginning
of this account, probably from suspecting their correctness.

At no¹. 12 is seen a sketch of this intei'esting animal ; 13 and
14 views of the Oestrus.

Linnaeus has remarked, that the Buphaga Africana draws forth
these larvae from the backs of the oxen. Syst. Nat. I. p. 154.
And in the Amaenitates Academicae is found also a repetition of the

above details respecting the Oestri, Vol. IV. p. 157 ; and where
the same circumstance is asserted in respect to the crows also
drawing them out from the backs of the rhein-deer : Cornices pro-
sequuntur Rkenoncm ut Oestros dorso inhcerentes extrahant et deglu-
tiant, quod quamvis Rheno non facile admittit, fatigatus tamen,ferre
scepius coactus est ut mihi narravit Dn. Er. Fiellstroem in Lapponia
ipse natus.

*** Oestri Cavicolat, or Face-Bots. Of the Oestrus Ovis, or

Sheep-Bot.

The eggs of this species I have not yet seen, the sheep being
Very shy under their attacks, which renders it difficult to approach
them near enough to see the actual operation ; the obscure colour
of the fly also adds to the difficulty. The sheep are exceedingly
annoyed with them, and to defend themselves get into the roads
in dry hot weather, and lie down along the dusty ruts, holding
their heads close to the ground, which makes it difficult for the
fly to get at them ; at other times one finds them standing up,
with their heads held low, almost to the earth, and the nose
turned between the fore legs, their nose being nearly in contact
with the ground. This mode of defence must render the attack
of the fly exceedingly difficult; at other times, when in the open
field, they congregate together, forming a dense compacted mass
or phalanx, which, except to the exterior ones, is scarcely acces-
sible to the fly, the noses of the greater part of them pushed
against each other, or held nearly close to the ground ; in this
way those placed in the centre must be very secure.

The manner in which this species deposits its ova, has not, I
believe, been described ; nor is it easy to see, though close to
the animal at the time, exactly in what way this is accomplished,
owing to the rapid motion and obscure colour of the fly, and the
extreme agitation of the sheep ; but from the actions of the sheep

afterwards, and the mode of defence it takes to avoid it, there is
little doubt that the egg is deposited on the margin of the nos-
tril. The moment the fly touches this part of the sheep, they
shake their heads, and strike the ground violently with their fore
feet, at the same time running away, and holding their noses close
to the ground, and looking about them on every side to see if
the fly pursues, and as they go along they often smell also to the
grass, and look anxiously into it, lest one should be lying in wait
for them ; if they observe one, they gallop back again, or take
some other direction. As they cannot, like the horses, take
refuge in the water, they have recourse to a rut, dry dusty road,
or gravel-pit, as a defence, as we have before remarked. PI. II.
fig. 16.

Observations on these flies are best made in dry weather, and
during the heat of the day, when by driving the sheep from their
retreats, the attack of the fly and the emotions of the sheep are
easily observed.

I imagine the nostril becomes highly inflamed and sore, from
their repeated attacks, and the consequent rubbing of the nose
against the ground, which, together with certain instinctive
apprehensions of these flies, occasion their touch to be so much
dreaded.

From the difficult and precarious mode these Oestri pursue in
depositing their eggs, they cannot succeed in depositing but a
few in each sheep ; whereas if on the contrary they actually
entered those cavities of the face to effect it, they must deposit
them all, and in one subject, the improbability of which in re-
spect to the other species is already stated.

Of the Larva. From one to seven or eight are generally found
in the cavities of the face, what are called by anatomists of the
human, the maxillary and frontal sinuses, but which in quadru-
peds are cavities of considerable extent and magnitude, and the
thin flexible bones which constitute them are covered with a

dense white membrane, upon the secretions of which they feed,
and these membranes are found more or less inflamed by then-
presence.

Vallisneri has remarked, that Alexander Trallien, a famous
Greek physician of the sixth century, relates the following anec-
-dote, which has an undoubted reference to these larva?, that
" Democrites, an Athenian, being subject to fits of epilepsy, de-
termined to consult the oracle at Delphos for a remedy, and
received for answer,

« Quos madidis cerebri Iatefaris procreare capella
Dicitur humores, vermem de vertice longum."

An old man of eighty years, explained to him the fact of the
existence of such worms, and pointed out the means of obtain-
ing them by a sack tied about the nose of the sheep, into which
they were received on falling from the sinuses. And this way
also was employed by Vallisneri and Reaumur.

When young these larvae are perfectly white and transparent,
except the two horny plates, which are black. As they increase
in size the upper side becomes marked with two transverse brown
lines on each segment, the anterior one shorter and narrower
than the posterior; and some spots are also seen on the sides.
The body consists of eleven segments. See fig. IJ.

I procured about the middle of June some full-grown larva? of
the QE. Ovis, from the inside of the cavities of the bone which
supports the horns of the sheep. They are nearly as large as
those of the GE. Equi, of a delicate white colour, flat on the
under side, and convex on the upper ; having no spines at the
divisions of the segments as the Gastricola?, but are provided
with tentacula at the small end. The other end is truncated
with a prominent ring or margin, which serves the same purpose *
in an inferior degree as the lips of the QE. Equi and haemorr-

hoidalis, by occasionally closing over, and cleaning the horny
plate, from the mucus and pus of the membranes, with which it
is subject to be smeared and prevented from performing its office.
When this margin opens after closing over the plate, it occasions
frequently a slight snap from the sudden admission of the air.

They move with considerable quickness, holding with the ten*
tacula as a fixed point, and drawing up the body towards them.
On the under side of the larva is placed a broad line of dots,
which, on examination with glasses, appear to be rough points,
serving perhaps the double purpose of assisting their passage
over the smooth and lubricated surfaces of these membranes, and
of exciting a degree of inflammation in them where they rest, so
as to cause a secretion of lymph or pus for their food.

I have mostly found these animals in the horns and frontal
sinuses, though I have remarked, that the membranes lining
these cavities were hardly at all inflamed, while those of the
maxillary sinuses were highly so. From this I am led to suspect
they inhabit the maxillary sinuses, and crawl, on the death of
the animal, into these situations in the horns and frontal sinuses.
The breeds of these, like the (E. Bovis, do not appear con-
fined to any particular season, for quite young and full-grown
larvae mav be found in the sinuses at the same time.

When full-grown they fall through the nostrils, and change to
the pupa state, lying on the earth, or adhering by the side to a
blade of grass. See fig. 18.

The fly bursts the shell of the pupa in about two months.
See fig. 19, 20, and trie veins of the wing, fig. 21.

On their Effects. The sheep are particularly subject to verti-
ginous diseases, which the agitations and irritations these ani-
mals occasion may tend to prevent. In the sheep it will be
^ much more difficult than in horses' to prevent or destroy them,
particularly if they are seated in the maxillary sinuses: in this

case trepanning would be insufficient, as they would probably be
concealed in the convolutions of the turbinated bones.

Perhaps the removal of the sheep to a distant pasture during
the months of June and July, while the greatest part of the Bots
are yet on the ground in the chrysalis state, and not bringing
them on the pasture again till the setting in of the winter, would
be the means of destroying them most effectually ; and if re-
peated for two or three years in succession where they are parti-
cularly troublesome, the farmers might eventually find their
account in it.

The male flies are found not unfrequently sticking to pales
and walls about sheep pastures.

Some large flies living in the backs of animals have of late
years been found in America, and have been referred to this
family ; I am, however, of opinion after more mature examina-
tion, that they are not truly Oestri, but should constitute a dis-
tinct genus ; their bodies are for the most part without hair
and smooth, and their antennae plu mated, in which they make
an approach to the plumated division of the genus Musca, as
the Musca, Ccesar, Cadaverina, Vomitoria, Mortuorum, Sfc.

For those I have seen I have been indebted to my much-
esteemed friend, John Francillon, whose liberality and splendid
collection of insects need not my poor encomiums ; he received
them from the American states of Georgia: and we are indebted
for what we know of their habits to his ingenious correspondent,
the indefatigable John Abbots, of the Savannah, who communi-
cated drawings and the insects themselves to my friend.

I propose to give an outline figure of three species of this
genus, from his cabinet, with the larva and chrysalis of one of
them ; and one new one from my own, which was purchased
from Dairy's Cabinet, being all the species I have hitherto seen,

The above indefatigable labourer in natural history in one of
his communications states, that in Georgia these flies are termed
the Rabbit Flies, as they infest the hares and rabbits of that
country. " A rabbit being catched," he says, " I observed
creeping out of the skin a worm, (see fig. 24,) which being full
fed, went into the ground, the 2nd of August. It feeds between
the skin and the flesh, seldom more than two at one time ; it
changed into chrysalis (see fig. 25,) and the fly appeared the 13th
of the September following, by pushing out a kind of door, (see
fig. 26.) The skin of the chrysalis was thick, and hard as wood.
The fly when it came out had a kind of bladder to its
mouth, &c." As the face of most flies on their issuing from the
chrysalis is so inflated, there is nothing singular in this ; that all
which appears to be interesting in this communication is con-
tained in the above extract.

I described one of these singular flies, the Cuniculi, in my
paper sent formerly to the Linnean Society, and ventured to
suggest, whether it might not be possible that these immense flies
have formerly belonged to some of those large animals whose
existence is no longer known, but whose bones are from time to
time discovered in the earth in various parts of the globe, and
that on their destruction they resorted to these small animals as
a substitute of necessity.

We may remark in concluding this brief account of them, that
if these insects should ever be brought to the aids of veterinary,
or other medicine, their effects would be much more powerful
than those of the Oestri, from their magnitude and roughness.
For distinction I have conferred on them the generic name of
Cuterebra,

OESTRUS. Antenna, articulis tribus, ultimo subgloboso seta antice
instructo, in foveis duabus frontis demersae. Os, apertura
simplex, neque ullo modo exsertum. Palpi, duo biarticu-
latij, apice orbiculares in depressione utrinque oris siti.
Alarum membrana laxa et subrugosa.

* Tamil. GASTRICOL^E.---------CHYLIVOR^E.

Larvae in Ventriculo Equi enutriuntur, stomachi interiori adheerent
corniculis duobus falciformibus acutis utrinque oris sitis. Ala-
rum tracheae seu Trachypterce usque ad marginem extreinam aloe
protenduntur. Corpus parcius pilis obtectum. Tab. I-fig. 16,23,

1. Equi, Oestrus. Alis albidis, fascia media punctisque duobus nigris extimis

Tab. I. fig. 13, 14.

Bovis Oe. Alis maculatis thorace flavo fascia fusca abdomine flavo
apice nigro. Linn. Syst. Nat. p. 969. 1. Faun. Suec. 1730.

Raii Hist. Ins. p. 271. Musca bipennis Oestrum dictus.

Oe. Bovis Fabricii Sp. Ins. p. 398.

Oe. Hcemorrhoidalis. Gmelin Syst. Nat. p. 2810.

Be Geer Hist. Ins. p. 291, pi. 15, fig. 16.

Geoffroy Hist. Ins. II. p. 456, n. 3.

Olivier Encyclopedic Methodique. Vide Estre.

Habitat in Pratis inter jumenta ; deponit ova in Genubus, lateribus,
jubaque Equorum.

Descrip. Apis mellificse magnitudinis. Caput latum, obtusum
Frons alba membrana nudiuscula, verticeque piloso, ferrugineo.
Oculi nigricantes in foeminis minores et distantiores. Antennae, glo-
bosse, compressse c. seta antice porrecta. Thorax griseus inter alas
obscurior. Scutellum fasciculis 2. pilosis. Abdomen luteo-ferru-
gineum, maculis punctisque (in maribus precipue) incisurarum
nigris. Aloe albidee neque diaphans quodem aureo colore relu-
eentes cum fascia pone medium flexuosa et in extrema alse maculis
duabus rotundatjs nigris. Punctum minimum atrum exstat in
eosta versus basin alee. Pedes palidiores, lutei, Tarsi simplices,
Unguiculis atris incurvatis posticis divergentibus squamulisque
duabus paleaceis clavatis.

Mas. Abdomen obtusum pube incurvata et forcipibus duobus atris
transversis quae vaginam muliebrem corripiunt et peni adducuut.

Fcemina. cum cauda elongata atra, ultimum segmentum vaginale,

66*

subcylindricum et superne fissum quo modo comprimit, extrudit-
que ovum.

Ovum, album elongatum apice in obliquum sectum, cum valvula
larvam emittere.

Larva, cute densa tecta, ovata, teres, postice truncata, antice capite
attenuate ore longitudinali corneo labiis duobus et unguiculis
duobus atris utrinque oris recurvatis quibus stomacho interno im-
pendet. Ad marginem segmentorum spinis rigidis deorsum speetan-
tibus duplice alterna serie obsita. Per menses duodecim nutrita
et ad maturitatem perducta, a stomacho solvitur, per intestinos
fertur tandem ano emissa, in humum decidit.

Pupa, ovalis, obscure rubra c. spinis brevibus rigidis uti in Larvis.
(3. Varietas cum alarum apice macula unica tantum oblonga et abdo-
mine dense tecto pilis ferrugineis. Specimen vidi in museo Lin-
neano quod certe varietas |3. Fn. Suec. No. 1730.
Oe, Vituli! Fabricii Syst. Ent. VI. p. 231.

Hcemorrhoidalis. Oe. Alis immaculatis fuscescentibus: abdomine atro, basi
albo apiceque fulvo. Tab. I. fig. 21, 22.
Oe. hEemorrhoidalis. Alis immaculatis thorace nigro: scutello pal-
lido, abdomine nigro basi albo apiceque fulvo. Linn. Syst. Nat.
II. 970. Fn. Suec. 1733.

Oe. Equi. (3 Fabr. Syst. Ent. Tom. 6. p. 232,

Oe. Bovis. Gmelin Syst. Nat. p. 2809.

Reaumur Hist. Inst. Tab. 35, f. 3. Larva T. 34, fig. 14.

Geoffroy Hist. Ins. 2, p. 455, n. 1.

Habitat in pascuis, deponit ova in labiis Equorum.

Descr. Oe. Equo dimidio minor. Frons alba tomentosa membra-
nacea. Oculi fusci in faeminis linea. nigra longitudinali. Thorax
pilis fiavo fuscis spatio inter alas atro, nudiusculo. Scutellum fus-
cum pilis albis porrectis obsitum. Abdomen atrum medio lucidum
basi albis apiceque pilis fulvis. Subtus pilosus cinereus, pedibus
pallidis longiusculis. Alee aureo-fuscae immaculatse, membrana
vix rugulosa. Halteres albidae.

Fvemince abdomen postice elongatum, incurvatum, atrum ; maris
cum prehensoribus masculinis sub ventre instructum.

Larva alba spinigera simillima priori at minor,

Puppa ovata brunnea spinis brevibus incisurarum.

Ovum, atrum, petiolo elongatum.

3. Veterinus. Oe. fernigineus, alis immaculatis lateribus thoracis, abdomineque
basi pilis albis. Tab. I. fig. 26, 27.

Oe. nasalis. Alis immaculatis, thorace ferrugineo abdomine nigro
pilis flavis. Lin. Syst. Nat. 969, 3. Fn. Suec. 1732. Reaumur
Hist. Ins. torn. IV. p. 551. PI. 35, fig. 3, 4, 5.

Habitat in Pascuis.

Descr. Oe. Equo minor, oblongior. Caput, thorax, et abdomen pilis
ferrugineis tecta. Alarum ortus abdominisque basis pilis albis
obsitee. Abdominis segmento secundo magis gibbo quam in reli-
quis tuberculis duobus hirtis. Subtus ferrugineo fuscus. Pedes
fusco ferruginei.

& Variat praecipue fceminis abdomine pene atro.

Larva elongata rubicunda glabra spinis minutis nisi ultimis duobu?
segmentis: in stomacho equi. Tab. 1. fig. 24.

#* CUTICOLyE.------------PURIVORiE.

Larvae sub cute animalium enutriuntur. Alarum trachea? seu
Trachypterce citra inarginem terminant per anastomosin. Tab.
2, f. 10. Squamce halterum grandiores. Corpus valde pilosum.

4. Bovis. Oes. alis immaculatis fuscis: thorace lineis quatuor interruptis gla-
bris atris: abdominis apice pilis fulvo-flavis. Tab. 2. f. 8, 9.

Vallisneri Opere, torn. I. tav. 28. f. 10.

Reaumur. Hist. Ins. torn. IV. p. 503, tab. 38, f. 7, 8.

De Geer Hist. Ins. torn. VI. p. 297, pi. 15. f. 22.

Schaeffer, Ins. Ratisbon, tab. 89, fig. 7.

Fishcher, Dissert, inaug. tab. 3. f. 5.

Med. Com. Vol. I. Larvee in Sinu frontis mulieris.

AngUs, Breeze, Brize, or Gad-fly.

Habitat in pascuis inter armenta in quorum dorso deponit ova.

Descr. Oe. Equo vix major fronte alba, undique tomentosa. Tho-
rax antice flavescens, in medio ater, lineis denudatis longitudina-
libus quatuor, postice cinerea. Abdomen basi cinereum fascia seu
cingulo in medio atro, apiceque pilis fulvoflavis. Squamce Halte-
rum magnffi nivese convexee. Pedes nigri, tarsis pallidis.

Fosmince abdomen, stylo attentuato atro, compression evolvendo.

Mas, tab. 1, ⁿg- 30, minor, abdomine obtusiore pube inflexo forei-
pibus masculinis. Oe. Erive/orum. Trans. Soc. Nat. Hist. In

Ericetis prima vere deprehensus a Dit. D. Leach prope Plymouth,
Devonian etiam prope Londinum. Anne distincta species ?

5. Tarandi. Oe. alis immaculatis : thoraceque postice lineis brevibus glabris qua-

tuoratris: abdomine fulvo. Tab. fig. 13, 14.

Habitat in Septentrionalibus. Larva in dorso Cerv. Tarandi.

Tarandi Oes. Alis immaculatis: thorace flavo fascia nigra: abdo-
mini fulvo apice flavo. Lin. Syst. Nat. p. 969.

Flor. Lappon. 360, n. 517. Act. Upsal 1736, p. 31, n. 23. Act.
Stockh. 1739, p. 121, torn. III. f. 5, 6. Lappis Curbma dicta.

Descr. Oe. Bovi simillimus at villosior. Frons flava pilosa vertice
antennisque atris. Thorax major flavus late in medio ater stigma-
tibus seu lineis elevatis, atris, 4, postice acutioribus. Alee subdia-
phanee squama halternm maxima margine inflexa squamulaque
insuper basin minori corrugata. Abdomen attenuatum saturate
fulvum hirsutum, basi thoraceque posterius albidis. Pedes atri
tibiis inferius pallidis. Tarsi rufi c. unguiculis longioribus, tenui-
bus divaricatis.

* * * CAVICOLyE.------------LYMPHIVOR^E.

Larvce in Cavitalibus Frontis Ovis Alarum Tracheae, seu Trachyp-
terai ad marginem alee tenuiorem haud pertingant nisi unicam,
basis aUe c. lobo reniformi vesicaque parva crenulata. Corpus
Icevet uberculis seligeris.

6. Ovis. Oes. Alis pellucidis basi punctatis : abdomini albo nigroque tesselato

versicolore.
Habitat inter pecora deponit ova in margine narium.
Ovis Oe. Alis subpunctatis abdomine albo nigroque versicolore.

Lin. Syst. Nat. p. 970. 5.
Vallisnere Opere, torn. I. t. 27.
Reaumur Hist. Ins. t. 35, f. 22. Larva 8, 9.
Geoffroy Hist. Ins. II. p. 456, n. 2,,
Descr. Oe. Equo minor, pilis scatentibus paucis, vertice capitis

punctis excavatis. Thorax cinereus, punctis elevatis atris, setige-

ris, lineisque quatuor nigris. Abdomen colore albido-cinereum

nigro maculatum fugaci. Supra aperturam oris processu parvo

conico.
Larva alba ovata, antice acuminata unguiculis dubbus, postice trun-

cata margine prominenti et squamulis duabus atris respiratoriis.

7. Cervi.

Superne convexa lineis punctisque nigris. Subtus plana in medio
segmentorum punctis asperis atris minutis notata. Pectus subtus
appendiculis 4 palpiformibus anterioribus longioribus.

Habitat intra cavos frontis ovium, evaditque per nares.

Oe.-------------------------------Reaumur. Ins. Tom. V. p. 67. PI. IX.

%. 2, 6.

Habitat Larva in Cavitate Pharyngis Cervorum.

Valde convenit cum Larva Oestri Ovini at major.

S. Stimulator. Oe. flavescens pilosus alarum basi thoraceque in medio atris.

Tab. I. fig. 28. Alarum trachea; f. 29.

Oe Pecorum. Fab. Syst. Ent. trompe? Ejusd.

Oe. Microcephalus. Dissert, preced. nostri.

Habitat in septentrionalibus.

Descr. Muscee bombylantis magnitudinis et staturae. Frons uti in
muscis provenit, in medio os absque proboscide barba alba, vertice
pilis flavescentibus. Oculi fusci nigro nebulosi cinctoque. An-
tennae globo atro seta porrecta: Thorax hirsutus, flavescens ad
incisuram mediam, exinde ater, etiam alee insertio atra subnu-
dus postice et scutello subnudo circumcincto pilis cinerascentibus.
Squama Halterum perlucidum decoloratum neque magnum. Alas
venis nigris abbreviatis conspicuis postice denticulatis.�Abdomen
breve subglobosum pilis parcius tectum rufo-cinereis utrinque
basi et postice pilis subfulvis ; subtus pilis cinereis hirtum in medio
atrum denudatum. Pedes omnino c. tarsis atri.

9. Phobifer. Oe. ater, alis plaga nigricante : thorace abdomineque postice rufis.
Tab. 2. f. 30.
Habitat in Georgia Americana I. Abbott. In museo arniciss. I.

Francillon.
Descr. Magnitudo muscse tenacis at gibbosior uti in Oe. hffimorrhoi-
dali et forsan ejusdem families. Oculi fusci. Thorax rufus utrin-
que pilosus uti scutellum. Alee a basi ad medium linealata seu
plaga nigricante ad costam, aliter diaphanee parum puculatae.
Squama halterum major diaphana. Abdomen atrum pilis fulvis
seu rufis tectum precipue ad extremitatem.
S

CUTEREBRA. Os, haustello corneo brevi in Fissura capitis recondite
Antenna tviarticulatse, ultima articulatio ovata, seta in-
structa plumosa. Palpi nulli.*

1. Cuniculi. Cu. nigra, thorace piloso lutescente in medio late antice nigro.

Habitat in Cuniculi et leporis dorso Americes. Tab. II. fig. 26.

Descr. Magnitudo, apis terrestris nostrse. Caput nigrum oculis
fuscis fronte porrecta. Thorax flavus hirtus antice ad medium
macula magna atra rotundata. Sculellum flavum. Abdomen
nigrum basi et lateribus segmentorum flavis, Alee fuses, lobo
baseos obscuriore. Subtus nigrum flavo variegatum. Pedes nigri,
tarsis latioribus. Larva fusca undique muricata aculeis minutis-
simis; fig. 24. Pupa fusca exasperata postice aperturis duabus
luteis respiratoriis. Tab. II. fig. 25.

2. Horripilum. C. nigra, thorace, abdomiuisque primo segmento pilosis flavis.

Habitat in Georgia apud Savannah Americes. J. Abbott. Tab. II..
fig. 27.
Descr. Magnitudo et statura omnino praecedentis at thorace absque
macula ista magna nigra quae ex aliquo casu denudasse suspicor.

?.. Cauterium. C. atra leevis, thoracis lateribus luteis, punctis tribus atris.

Habitat in America* sylvis prope flumen Ogeechense. J. Abbott.
Tab. II. fig. 28.

Descr. Minor C horripilo, Caput atrum thorace latius. Oculi
grisei, albo punctulati, orbitum anterius striis 4 niveis, inferius
utrinque oris luteum. Thorax ater lsevis convexus ad latera flavo
vellere tectus punctis tribus et orificio respiratorio atris. Abdomen
nigro-cyaneum infra atrum, punctis pallidis irroratum et ultimum
segmentum-utrinque. Alee, nigricantes quam in ceeteris obscuri-
ores. Pedes atri lucidi.

4. Purivora. C. coeruleo alba, Thorace capiteque punctis atris.

Oestrus buccalus. Fab.

Habitat in ArnericaU J. Abbott. Tab. II. fig. 29.

Descr. C. cauterio major, valde gibbus. Caput magnum thorace
latius, insuper atrum lucidum punctulatum maculis duabus in
vertice, et quatuor ante oculos majoribus, albis. Frons parte
inferiori cceruleo-alba seu argeuteo-caerulea, punctis lucidis octo
atris, medium par inferiorum quasi palpos semulantes, cum petiolo

* Corpus hujus generis muscavum leevius et cataphracta duriore obtectum precipue abdo-
inine. Alae in omnibus mihi visse coloratse, lobo baseos dissecto rotundato, et a posteriori
thoracis parte prodeuntes.

scissuree connexo. Thorax coeruleo-incanus antice lineis
obscuris nigris ad latera villosior maculis tribus atris. Scutellum
lineatum supereminet abdomen. Abdomen atro-coeruleum late-
ribus posticeque coerulescentibus nigro irroratum. Pedes nigri
femoribus rubris. Aloe fuscee lobo baseos dissecto nigricante.

OESTRUS. Antennae with three articulations the last globose with a
bristle in front deeply sunk in the head. Mouth a simple
aperture without a trunk. Palpi two, of two articulations,
last rounded, situated in a depression on each side the
mouth. Membrane of the wings lax and puckered.

* Stomach Bots.

\. Equi. Oe. The Knee Bot, or great spotted Horse Bot. Wings opake white,

with a golden tinge, a transverse black wave and two spots near
the extremity : a minute black raised dot near the base of the
wing. Abdomen reddish brown, with black spots and points.
Legs red. Female with lengthened abdomen, curving underneath:
male obtuse.

In meadows, laying its eggs or nits on the knees, mane, and sides
of horses.

Bgg white, oblong, pointed, the other extremity obtusely truncated
with a lid. Larva or Grub barrel-shaped, at one end tapering_?obtuse at the other, covered with a thick skin, beset with a double
row of prickles round each joint, alternately placed.

In the stomach of the horse, to which it adheres by two short black
hooks, one each side the mouth.

The Pupa or Chrysalis oval, dark red, rough with prickly points,
under dung.

2. Hemorrhoidalis. Ge« The Lip or Fundament Bot. Wings without spot, brown.
Face white, antennae in a black pit or depression. Body thinly
covered with hair, greyish in the middle of the thorax and abdo-
men black shining, base of the latter white, and extremity red
orange. Beneath grey, hairy. Legs pale red.
In meadows, laying its eggs on the lips of the horse.
Egg black, oblong with a petiolus or foot stalk.
Larva white, with spines or prickles like the former, but less and
rounder..

In the stomach of the horse,
round the segments.

Puppa red brown with small prickles

3. Veterinus. Oe. The Red, or Breast Bot%-. Wings clear, unspotted. Body-
oblong, tapering, covered with reddish yellow hairs ; sides of the
thorax and base of the abdomen with white tufted hairs.

In meadows. Larva oblong, coral red, smooth joints, rounded,
two last dark red.

In horses stomachs.,

** Skin Bots.

4. Bovis. Oe. Ox BoT or Gad Fly. Wings brownish unspotted. Thorax

with four smooth raised lines. Abdomen, base white, middle
black, end orange red. Legs black, with red feet. In meadows.

Larva or grub in the backs of cows. White, with eleven segments
or divisions, with a narrow and a broad line of rough points on
each.

/3 Vernalis, Small Ox Bot. Less than the former; colours more
obscure. I possess both male and female; whether a distinct
species or a variety produced by season, I am unable to deter-
mine. It also is found in America.

5. Tarandi. ^Oe. Rhein-DEER Bot. Wings immaculate. Thorax with four raised

short lines. Abdomen with orange hairs. Like the former, but
larger, more hairy, and of a darker orange. In Lapland, laying
its eggs on the back of the rhein-deer.
Larva white, black at the extremity.

*#* Face Bots.

6. Ovis. Oe. Sheep Bot. Wings transparent, minutely spotted near the base.

Abdomen reflecting white and black according to the light, in
squares. Thorax with raised black dots. Among sheep, laying
the egg on the margin of the nose. Larva white, with black
transverse lines and spots in the frontal cavities of the sheep

* In the cabinet of my esteemed friend, J. Francillon, there are specimens, sent by J. Abbott
from America, which I take to be of this species," though somewhat smaller, and the colours
much more obscure. He observes, that the parent fly lays its eggs on the breast of the horse.

FINIS.

W. Flint, Printer, Old Bailey, London.

ADDENDA 1848.

(Fj. Cent. c.

For a full description of this fly, (E. Cervi, we refer the reader to page 92 of our

Monograph, 2nd Supplement.

The following communication was sent by me to the " Zoologist " of my friend Edward Newman, No. ],for
January, for the year 1847.

Note on the Hot infesting the Stag.'�After considei'able delay, from various unforeseen causes, I am
enabled to present thy subscribers with a view of the larva and pupa of the bot of the deer, objects hitherto
quite unknown, I believe, to naturalists. Eeaumur has indeed given a representation of the larva of this
species, but it is evident, from the very elongated figure he has given of it, that it must have been dead
some time, and obtained this lengthened figure from putrefaction. This larva, several of which I have had
alive, so much resembles that of the GEstrus of the sheep, that they might be taken on a careless inspection
for one another, that of the deer is, however, somewhat proportionally longer and less angular. All
efforts to preserve them out of their locality in the throat of the stag seem hopeless; I have had many from
the New Forest by the kindness of the Superintendant there, and though kept on membranes and fed with
milk in a warm place, they uniformly died within forty-eight hours. The present specimen was so far
advanced in its growth that it assumed the chrysalis state, but died in that state and never came out.
Though positive proof still fail us, I am brought to the firmest conviction that the stag bot is no other than
the CEstrus pictus, found by my late friend George Samouelle, in the New Forest, and since taken in the
same place by our very worthy friend and excellent entomologist, J. C. Dale, Esq. ; and as there is no bot-fly
known in this country that we do not fully understand in all its states, so it brings us to the all but absolute
proof that it is no other than the CEstrus pictus, so called by Curtis in his excellent " British Entomology,"
and by the continental naturalists. This larva, with others, at different times was received by me by the
kind aid of my worthy friend John Bolt, of Lyndhurst, assisted by the kindly interference also of the present
forest-keeper and ranger, who desired any larvas found in the killed venison to be brought to him. Any
one desirous of seeing a good representation or figure of this species may consult my " Treatise " on this
genus, pi. 1, fig. 40, with nearly or quite all the other members in their respective changes of this truly
remarkable family.

Detrudator. � Cuterebra, nigra, holosericea, abdomine glabro cserulescenti nigro,
lateribus albo bicingulatis, posticeque rufo.

Habitat calidioribus Americes. Ex Museo Dom. Westwood. Yid. fig. 4.

Descr. Ceedit maximis hujus generis. Caput obtusum, vertice atro, inter
oculos rufum, ore et inferne late album hirsutum. Thorax ater holoseri-
ceus, infra insertiones alarum et subtus, albus. Halteres concavae conco-
lores, erectse. Alee longiores aurulento-fuliginosa?. Abdomen lsete ceeru-
leum ad latera cingulis duobus latis albis, apiceque hirsuto flavescenti
rufo. Pedes omnino atri tarsis prselongis articulis sagittato-acutis.

Atrox.�Cut. atra, glabra, abdomine ceerulescenti-atro marginibus segmentorum albis.

Habitasse creditor in Africa, v. fig. 5. Ex Museo D. Westwood.

Descr. Facile inter maximas hujus generis omnino atro ceerulescens,
lucidus. Thorax antice scabriusculus, postice glaber. Halteres scutellum
circumcingentes, erectae, maxima?. Alee parum puculatse, obscure aurulento,
fuliginosee. Abdomen latum, obtusum, incurvatum, atro cseruleum inci-
surarum marginibus, albis. Ad latera et subtus albo late conspersum.
Pedes atri geniculis tibiarum extus albicantibus.



* Gastricola	i. Oestrus JEqui C	Flaie 1.

trmWM^x

\



	AN ESSAY ON THE BOTS OF HORSES, AMD OTHER ANIMALS. By BRACY CLARK, F. L. S. VETERINARY SURGEON. LONDON- PRINTED FOR THE AUTHOR, AND SOLD AT NO. 17, GILTSPUR STREET, 1815.



	4 this case being for brevity omitted. Indeed the instances of its application are very numerous in our language. The way or reason that these Insects became so designated, is pretty manifest, from the Habits more particularly of the second species of this enumeration, or Hatmorrhoidalis, which being fully fed its growth completed, in quitting its habitation in the stomach, and passing through the intestines, does usually bang for some days upon the margin of the Fundament, be- neath the tail, then falling to the earth and forming a Chry- salis ; and in this state would attract more particular notice and attention, occasioning often serious inconvenience and dis- tress. So situated and observed, it was denoted the Bout Worm or End Worm, and by contraction Bot Worm ; and afterwards, for want of better epithets, the appellation became extended to the Fly produced by this worm, and we obtain Bot Fly, though it is obvious, as the fly never affects these situations, its appli- cation is improper, and has served to disguise and conceal the real origin of the name. Erroneous and strange notions were entertained in early times of these animals. What views the Romans had of them, we learn from a passage in Vegetius, an elegant veterinary writer in the time of Valentinian, in the fourth century. He says, " When a Humour is found in the anus of the Horse like a boiled bean, it is a sign of this disease (the Coriago) or hide- bound Horse, for it is a sanies from the wounds inflicted by small animals in the inside of the beast ;" in which it is evident he alludes to the second species, the hemorrhoidal or red-tailed Bot, which in hanging, as we have stated, to the extremity of the rectum, corresponds very tolerably in size and appearance to the boiled Bean he compares it to. Still more antiently than Hujusmodi passionis signum est (morbus coriaginosus) cum invenitur humor in ano fabae coctse similis : est namque sanies ex illis vulaeribus que bestioke in- trinsecus fecerunt. Ed. Manbeira, p. 63.



	6

	To feed the females ere the sun arise, Or late at night, when stars adorn the skies." Drydes. The next notice of these animals in point of antiquity that we have yet observed is with the Veterinary writers of Constantino- ple, as Absyrtus, Theomnestus, &c. who appear to have designated them by the term Teredines, {n^Smt,) perhaps on account of their cylindrical figure ; or it may be from their boring, as they apprehended, holes in the stomach, an apprehension and belief which prevails very much at this day among the ignorant, but is without foundation. The impressions or indentations they occasion upon the soft internal coats of the stomach, are often, it is true, pretty deep, but never, as far as we have seen, have pierced through the stomach; these indentations probably close and fill up again, after the Bot is removed; for the death of animals is certainly not designed in their use, The Veterinarians of Constantinople for their cure direct us to extract them from the fundament with the fingers, and then kill them by strewing hot ashes over them ; by which recommendation it would appear that they entertained some obscure apprehensions of their afterwards coming to something hurtful, if permitted to live, though it is probable their notions were very obscure, if they had any, of their real trans- formations. The same Veterinarians, I observe, have also made an allu- sion to the Bot which infests the head of the Stag; of which, excepting what Reaumur has informed us, we know no more at this day than what they did, at least that I am acquainted with. Reaumur describes it as existing in a sac of the Fauces. What the complete Insect is, we are as yet unacquainted ; and I mention it here to excite the farther prosecution of this object, which to those who have leisure and opportunity, and



	*

	20 suspect near an hundred at least are lost for one that arrives at the perfect state of a fly. In the first place, in the depositing the eggs not a little interruption is given to the female by the movements of the Horse : the eggs when deposited may remain on the hairs untouched by the animal, unless some casualty makes him lick those parts to which they adhere, and when ripe, or if hatched and opened by rain, or other moisture, the larvae may come forth, and crawl about till they die. In the mouth of the animal they have the dreadful ordeal of the teeth and mastication to pass through. On their arrival at the stomach, they may pass, mixed with the mass of food, into the intestines ; and, when full grown, on dropping from the anus to the ground, a dirty road or water may receive them. If on the commons, they are in danger of being crushed to death, or of being picked up by the birds, who so frequently for food attend the footsteps of the cattle. By such contingencies as these, Providence has wisely prevented their too great increase, and the total destruction of the animals they feed on. The egg is glued on the hair with the broad end downward, (see fig. 2, 3,) and is thus well disposed for the Operation of the tongue in removing the operculum. This operculum is of an oval figure, surrounded with a prominent margin. The micro- scope shews the case of the egg to be shagreened in squares, or divided by lines longitudinally and transversely disposed. Of the Larva or Grub of the Oestrus Equi, or spotted Horse Bot. At its first hatching it is, as we have observed, a small active worm, long in proportion to'its thickness, but as its growth ad- vances, it becomes proportionably thicker and broader, and beset with bristles. Some of these Larva?, when about two-thirds grown, are represented in Plate I. fig. 5, adhering to the stomach. They are



	35 was opake or milky, with hardly any redness about them, though the last segment was somewhat faintly tinged with red. But there appears in the spines or bristles a peculiarly distinctive cha- racter, for they are in a single row only, and regularly placed in a line, and the microscope could hardly discover that their points were black, being minutely so, and hardly visible to the naked eye, while the other species were distinctly so to some distance, in make and other circumstances they resembled the Equi, but were not above half their size. Having stated these circum- stances, I leave the further investigation of them to the curious. The real Chrysalis of Veterinus I once found in the neighbour- hood of Worcester, in a meadow below Perry Wood, between it and the city, under some horse dung ; and the figure of it was, as near as I can remember, for I threw it away after the Fly came out, much like figure 26, which is done from memory, for at that time I had no prospect of ever having to write on these subjects. This Fly, after it left the Chrysalis, being confined under a glass in my window, became, if I remember right, singularly active and impatient, and destroyed in its rage one of its wings, drawing it towards its mouth with its legs, and devouring it, as it appeared, and whirling round with considerable velocity and noise upon its back. Whether other flies so confined would do the same I know not. I think Reaumur's figures I have referred to are certainly meant for this species, but the figures 1 and 2 are evidently two differ- ent Chrysalides, though given for the same. The one is of Has- morrhoidalis or Equi, the other smoother, and probably of this species. Tom. IV. pi. 35. The Larva of this species is not given by him at all, but in the preceding plate there is a good figure of the Larva of the Hasmorrhoidalis, which he considered the same, and the Flies 9 and 10 are the Hasmorrhoidalis, though badly executed. As far as I remember, the Fly of Veterinus, in making



	36 its way out of the case of the Chrysalis, broke away the three or four last segments of the small end, leaving a ragged edge to the opening, but not a regular marginated operculum as given in Reaumur's figure, and which operculum is so remarkable in the Chrysalis of the Oestrus Bovis. This Insect proved a male, fig. 26 ; and I afterwards in the cabinet of Linna3us, obligingly presented to my observation by Sir James Edward Smith, found the female, fig. 27, with a short stylus to the abdomen. Some other specimens of this species were found in this cabinet, taken from the collection of Hudson, the ingenious author of the Flora Anglica, nearly spoiled, and entangled in the melted wax with which his drawers were covered, as was the custom of those days before the use of cork. A misera- ble fire consumed his house, and nearly his Herbarium, and occa- sioned the melting of the wax before mentioned. Linnaeus supposed this Insect entered by the nostrils and lived there as the other did by the fundament ; but as no insect would destroy its own wings, and so miserably punish itself, we have ventured to obliterate the name, that erroneous notions should not be suggested by it.�For its description see the conclusion of this dissertation. It appears to me that more certain information might be ob- tained respecting this and the other species that infest the domestic animals, by a very simple method, and which I propose next year to endeavour to prosecute, if my health and present views re- main. For this end I propose to procure from the slaughter- houses, and the stomachs of dead horses there, such of these ob- scure species in the Larva state as it may be desirable to investi- gate ; and since they cannot be fed with any prospect of success out of the body, I intend to inclose them in a ball of meal, and administer them to my own horse, as balls of physic are admini- stered, and in his stomach they will perfect their growth. I next intend to have a stall boarded at bottom and closely jointed, with



	42 years, should have their wholesome stimulus, I cut off the hairs from another horse charged with the Bot's eggs, and gave him about three dozen of them. He afterwards grew fatter, and in better condition than I had ever known him, whether from their effects or not I do not undertake to determine, but think it not improbable they contributed to it. In Nasal Farcy Gleets of Horses, I have followed this sugges- tion of stimulating the stomach by Cantharides in small doses, and by the Sulphat of Zinc, with great success, curing several that were considered g'andered. The domestic animals in a particular manner appear to be the objects of this species of natural stimuli or vellicatories, which as they are also frequently forced by man into unnatural exer- tions and unhealthy situations to suit his views and convenience, so therefore they may stand more in need of this sort of protec- tion. Their impressions may be hardly cognizable to the senses, and produce nevertheless powerful effects upon the stomach, and thence to the system at large, as we see in the case of spices given with food, and fomentations, mild blisters and sinapisms to the skin. How dirty in warm climates would men become, if it was not for the fear of the increase of vermin, that they can stimulate to industry therefore is certain, and so to health. Animals would become inactive in warm weather, perhaps fatally so, if it was not for the stimulus of flies and other insects, which by teazing prevent it. Those who consider the Bots as a plague would no doubt be desirous of being informed how they should best destroy them. One great utility in the study of natural history is, that it affords us a knowledge of the habits of these animals, and by these we are taught the most effectual measures for this purpose. It is indeed truly difficult to detach them from the stomach by any medicines or poisons administered internally, though there are not



	I

	44 extremity of the rectum, and should be removed by the fingers. The destruction of a single one at this season of the year is not only the death of an individual and its effects, but the almost certain destruction of a numerous progeny ; it is also useful in preventing the irritation which the spines of the Bot occasion to the anus, which irritation becomes very distressing to the ani- mal if he is used on the road, occasions him to move awkwardly, wriggle himself about, and to be sluggish, and though beaten severely he soon relapses again into his awkward manner of going ; which as this happens generally in warm weather, is most com- monly attributed to mere laziness. Some further remarks on their probable effects we leave till we treat of the Cuticolar and Cavicolar Oestri. * * Second Family, CuticoLjE. The Oestrus Bovis, or Gad Fly. Of all the European species of this genus, this is the largest, and is not unfrequently seen in country situations in the backs of oxen and cows. They form tumors as large as pullets eggs on the sides, about the back and loins. See their appearance, Plate II. fig. 2, a the tumor or abscess, b the external opening. With us among the country people they are called Warbles, Wornils, Wormuls, and sometimes Bots. When I first took up the investigation of these animals, I was in considerable perplexity what this species could be, since I possessed the Oestrus Bovis of Linnaeus, agreeing perfectly with the description, and which was a Horse Bot ; nor had I then seen the writings of Vallisneri or Reaumur, which, as Linnaeus had seen and referred to, I did not suppose could have fallen into such an error as to have omitted entirely this remarkable species, or have confounded it with the Equi, but it so proved, and on obtaining the perfect insect from the back of the cow, the mys-

	♦



	49 these hooks, erected by the muscles of the skin, the animal raises or depresses himself at pleasure, or turns about in the abscess and finally crawls out of it when ripe. The use of the terminal ten- tacula, observable in the Gastric species, would have been useless in this, as the oval form of the abscess retains them in their abode sufficiently secure. And b_y the motion of the larva in the abscess these hooks, by irritating the surface of the sac, produce a discharge of pus for sustenance. In what manner the nourishment is received by this larva is not immediately discoverable. Indeed, it was not known to me till an unexpected circumstance led me to its discovery ■ on im- mersing one of these larva? in warm water with a view to rid it of pus and slime, I observed a considerable quantity of pus to be ejected from an aperture, which at other times was closed, this was at first considered to be the mouth; it, however, was found on further research to be the real anus of the larva, for it is in the upper part of the larva, or that end which is applied to the external opening in the skin, (where may be also observed two small horny plates,) which are found on dissection to close the ex- tremities of the trunks of two large air vessels. Near to these plates, and somewhat above them, this minute puncture is discernible. At other times, when closed, it was discernible with the utmost difficulty. At fig. 3. is represented this aperture, a. together with the two horny plates, which close up the air vessels, being a view, very considerably magnified, of this upper extremity of the larva. From a first view, this part would appear to be the head of the larva, being uppermost in the abscess; but as it is found to pro- duce the extremity of the abdomen in the future insect, it must, therefore, be considered as the tail; and the above-mentioned minute aperture is undoubtedly the anus, and is found to be in conformity to the same situation of the anus in others of this N



	50 genus. And this would seem to render it manifest, that through these plates they receive the air, and emit it by the spiracula. At the lower end of the larva, fig. 3. a small indentation may, with attention, be observed, which is the mouth of the larva. It is a simple aperture, and altogether unprovided with any of the apparatus belonging to the mouths of larvae in general; and near the mouth are seen two black points of horn, which appear to be perforated in the centre, and are found by dissection to be the termination of two considerable branches of the air tubes, and correspond to the two nipples on the first segment of the larva of the QE. Equi. An enlarged view of the mouth and inferior part of the larva of the QE. Bovis is seen in fig. 4. Round the orifice of the mouth are placed some projecting mamilla?, which are imperforate, and perhaps serve the purpose of feelers. The intestinal canal in this larva is a simple membranous tube, which extends from one extremity to the other, and serves the double purpose of stomach and intestine. In the larva of the Oestrus Bovis there are only two principal trunks of air vessels, which are connected near their origin by a lateral trunk. From these trunks branches are seen passing in every direction through the parenchyma or matter of the body of the insect, some going to the intestine, others to the skin, and a greater number appear to be forming an anastomosis with each other. When young the larva is smooth, white, and transparent ; as it enlarges it becomes browner ; and about the time it is full grown it is totally of a deep brown colour. The larva having attained its full growth and size, effects its escape from the abscess by pressing against the external opening, which occasions its enlargement by the points pressed upon being- absorbed, and the skin also may give way and extend itself under- their impression. When the opening has obtained the size of a



	54 the Laplander to quit his abode several months of the year, and oblige him to go with his Rheins into the Upland Alps, in order to avoid their effects. The gnats or musquitoes also, in these regions are more troublesome than in any other part of the world; so that not only the rigours of the climate, the unproductiveness of the earth, and the hard condition of life, but the very insects appear to contribute to drive men from these situations into more hospitable latitudes. The Rhein-deer Bot had attracted very little notice till the writings of Linnaeus presented many interesting details respecting them to the lovers of natural history; and from his various scat- tered notices or memoirs we have extracted the following details : In the Flora Lapponica, p. 360, in describing the Agarics and Lichens of this part of the world, he introduces his remarks on the Rhein-deer Gad-Fly ; as the Rhein-deer is chiefly fed during the winter on one of these, the Lichen rangiferinus, which is very abundant in the north, as though provided for them, and is serv- ing perhaps in some instances also, as a covering from the incle- mency of the weather to vegetables. He afterwards in a sort of journal of his tour, written in Swe- dish in the Acta Stockholmia for 173.9, p. 119, gives further parti- culars of their history. And in the Acta Upsaiiensia, 1736, p. 102, he enters again on this subject with some variations. Their depredations he describes as most bitterly felt by the inhabitants of these regions ; and after a few pious and admiring ■� reflections on the ways of Providence in providing for these Flies in their delicate and tender larva state, he observes, that in his journey into Lapmark in the year 1732, he found all the inhabi- tants had quitted their plains and woodlands for the hilly country and Alps. One only he found dwelling there with his Rhein-deer (Rheno), whose horns, soft, tender, and sore, were miserably punctured by the Tabani till they distilled blood ; and that the gnats also joined in the persecution with their little trunks con�



	59 above details respecting the Oestri, Vol. IV. p. 157 ; and where the same circumstance is asserted in respect to the crows also drawing them out from the backs of the rhein-deer : Cornices pro- sequuntur Rkenoncm ut Oestros dorso inhcerentes extrahant et deglu- tiant, quod quamvis Rheno non facile admittit, fatigatus tamen,ferre scepius coactus est ut mihi narravit Dn. Er. Fiellstroem in Lapponia ipse natus. *** Oestri Cavicolat, or Face-Bots. Of the Oestrus Ovis, or Sheep-Bot. The eggs of this species I have not yet seen, the sheep being Very shy under their attacks, which renders it difficult to approach them near enough to see the actual operation ; the obscure colour of the fly also adds to the difficulty. The sheep are exceedingly annoyed with them, and to defend themselves get into the roads in dry hot weather, and lie down along the dusty ruts, holding their heads close to the ground, which makes it difficult for the fly to get at them ; at other times one finds them standing up, with their heads held low, almost to the earth, and the nose turned between the fore legs, their nose being nearly in contact with the ground. This mode of defence must render the attack of the fly exceedingly difficult; at other times, when in the open field, they congregate together, forming a dense compacted mass or phalanx, which, except to the exterior ones, is scarcely acces- sible to the fly, the noses of the greater part of them pushed against each other, or held nearly close to the ground ; in this way those placed in the centre must be very secure. The manner in which this species deposits its ova, has not, I believe, been described ; nor is it easy to see, though close to the animal at the time, exactly in what way this is accomplished, owing to the rapid motion and obscure colour of the fly, and the extreme agitation of the sheep ; but from the actions of the sheep



	I

	62 hoidalis, by occasionally closing over, and cleaning the horny plate, from the mucus and pus of the membranes, with which it is subject to be smeared and prevented from performing its office. When this margin opens after closing over the plate, it occasions frequently a slight snap from the sudden admission of the air. They move with considerable quickness, holding with the ten* tacula as a fixed point, and drawing up the body towards them. On the under side of the larva is placed a broad line of dots, which, on examination with glasses, appear to be rough points, serving perhaps the double purpose of assisting their passage over the smooth and lubricated surfaces of these membranes, and of exciting a degree of inflammation in them where they rest, so as to cause a secretion of lymph or pus for their food. I have mostly found these animals in the horns and frontal sinuses, though I have remarked, that the membranes lining these cavities were hardly at all inflamed, while those of the maxillary sinuses were highly so. From this I am led to suspect they inhabit the maxillary sinuses, and crawl, on the death of the animal, into these situations in the horns and frontal sinuses. The breeds of these, like the (E. Bovis, do not appear con- fined to any particular season, for quite young and full-grown larvae mav be found in the sinuses at the same time. When full-grown they fall through the nostrils, and change to the pupa state, lying on the earth, or adhering by the side to a blade of grass. See fig. 18. The fly bursts the shell of the pupa in about two months. See fig. 19, 20, and trie veins of the wing, fig. 21. On their Effects. The sheep are particularly subject to verti- ginous diseases, which the agitations and irritations these ani- mals occasion may tend to prevent. In the sheep it will be ^ much more difficult than in horses' to prevent or destroy them, particularly if they are seated in the maxillary sinuses: in this



	67 3. Veterinus. Oe. fernigineus, alis immaculatis lateribus thoracis, abdomineque basi pilis albis. Tab. I. fig. 26, 27. Oe. nasalis. Alis immaculatis, thorace ferrugineo abdomine nigro pilis flavis. Lin. Syst. Nat. 969, 3. Fn. Suec. 1732. Reaumur Hist. Ins. torn. IV. p. 551. PI. 35, fig. 3, 4, 5. Habitat in Pascuis. Descr. Oe. Equo minor, oblongior. Caput, thorax, et abdomen pilis ferrugineis tecta. Alarum ortus abdominisque basis pilis albis obsitee. Abdominis segmento secundo magis gibbo quam in reli- quis tuberculis duobus hirtis. Subtus ferrugineo fuscus. Pedes fusco ferruginei. & Variat praecipue fceminis abdomine pene atro. Larva elongata rubicunda glabra spinis minutis nisi ultimis duobu? segmentis: in stomacho equi. Tab. 1. fig. 24. #* CUTICOLyE.------------PURIVORiE. Larvae sub cute animalium enutriuntur. Alarum trachea? seu Trachypterce citra inarginem terminant per anastomosin. Tab. 2, f. 10. Squamce halterum grandiores. Corpus valde pilosum. 4. Bovis. Oes. alis immaculatis fuscis: thorace lineis quatuor interruptis gla- bris atris: abdominis apice pilis fulvo-flavis. Tab. 2. f. 8, 9. Vallisneri Opere, torn. I. tav. 28. f. 10. Reaumur. Hist. Ins. torn. IV. p. 503, tab. 38, f. 7, 8. De Geer Hist. Ins. torn. VI. p. 297, pi. 15. f. 22. Schaeffer, Ins. Ratisbon, tab. 89, fig. 7. Fishcher, Dissert, inaug. tab. 3. f. 5. Med. Com. Vol. I. Larvee in Sinu frontis mulieris. AngUs, Breeze, Brize, or Gad-fly. Habitat in pascuis inter armenta in quorum dorso deponit ova. Descr. Oe. Equo vix major fronte alba, undique tomentosa. Tho- rax antice flavescens, in medio ater, lineis denudatis longitudina- libus quatuor, postice cinerea. Abdomen basi cinereum fascia seu cingulo in medio atro, apiceque pilis fulvoflavis. Squamce Halte- rum magnffi nivese convexee. Pedes nigri, tarsis pallidis. Fosmince abdomen, stylo attentuato atro, compression evolvendo. Mas, tab. 1, ⁿg- 30, minor, abdomine obtusiore pube inflexo forei- pibus masculinis. Oe. Erive/orum. Trans. Soc. Nat. Hist. In



	68 Ericetis prima vere deprehensus a Dit. D. Leach prope Plymouth, Devonian etiam prope Londinum. Anne distincta species ? 5. Tarandi. Oe. alis immaculatis : thoraceque postice lineis brevibus glabris qua- tuoratris: abdomine fulvo. Tab. fig. 13, 14. Habitat in Septentrionalibus. Larva in dorso Cerv. Tarandi. Tarandi Oes. Alis immaculatis: thorace flavo fascia nigra: abdo- mini fulvo apice flavo. Lin. Syst. Nat. p. 969. Flor. Lappon. 360, n. 517. Act. Upsal 1736, p. 31, n. 23. Act. Stockh. 1739, p. 121, torn. III. f. 5, 6. Lappis Curbma dicta. Descr. Oe. Bovi simillimus at villosior. Frons flava pilosa vertice antennisque atris. Thorax major flavus late in medio ater stigma- tibus seu lineis elevatis, atris, 4, postice acutioribus. Alee subdia- phanee squama halternm maxima margine inflexa squamulaque insuper basin minori corrugata. Abdomen attenuatum saturate fulvum hirsutum, basi thoraceque posterius albidis. Pedes atri tibiis inferius pallidis. Tarsi rufi c. unguiculis longioribus, tenui- bus divaricatis. * * * CAVICOLyE.------------LYMPHIVOR^E. Larvce in Cavitalibus Frontis Ovis Alarum Tracheae, seu Trachyp- terai ad marginem alee tenuiorem haud pertingant nisi unicam, basis aUe c. lobo reniformi vesicaque parva crenulata. Corpus Icevet uberculis seligeris. 6. Ovis. Oes. Alis pellucidis basi punctatis : abdomini albo nigroque tesselato versicolore. Habitat inter pecora deponit ova in margine narium. Ovis Oe. Alis subpunctatis abdomine albo nigroque versicolore. Lin. Syst. Nat. p. 970. 5. Vallisnere Opere, torn. I. t. 27. Reaumur Hist. Ins. t. 35, f. 22. Larva 8, 9. Geoffroy Hist. Ins. II. p. 456, n. 2,, Descr. Oe. Equo minor, pilis scatentibus paucis, vertice capitis punctis excavatis. Thorax cinereus, punctis elevatis atris, setige- ris, lineisque quatuor nigris. Abdomen colore albido-cinereum nigro maculatum fugaci. Supra aperturam oris processu parvo conico. Larva alba ovata, antice acuminata unguiculis dubbus, postice trun- cata margine prominenti et squamulis duabus atris respiratoriis.



	ADDENDA 1848.

	(Fj. Cent. c. For a full description of this fly, (E. Cervi, we refer the reader to page 92 of our Monograph, 2nd Supplement. The following communication was sent by me to the " Zoologist " of my friend Edward Newman, No. ],for January, for the year 1847. Note on the Hot infesting the Stag.'�After considei'able delay, from various unforeseen causes, I am enabled to present thy subscribers with a view of the larva and pupa of the bot of the deer, objects hitherto quite unknown, I believe, to naturalists. Eeaumur has indeed given a representation of the larva of this species, but it is evident, from the very elongated figure he has given of it, that it must have been dead some time, and obtained this lengthened figure from putrefaction. This larva, several of which I have had alive, so much resembles that of the GEstrus of the sheep, that they might be taken on a careless inspection for one another, that of the deer is, however, somewhat proportionally longer and less angular. All efforts to preserve them out of their locality in the throat of the stag seem hopeless; I have had many from the New Forest by the kindness of the Superintendant there, and though kept on membranes and fed with milk in a warm place, they uniformly died within forty-eight hours. The present specimen was so far advanced in its growth that it assumed the chrysalis state, but died in that state and never came out. Though positive proof still fail us, I am brought to the firmest conviction that the stag bot is no other than the CEstrus pictus, found by my late friend George Samouelle, in the New Forest, and since taken in the same place by our very worthy friend and excellent entomologist, J. C. Dale, Esq. ; and as there is no bot-fly known in this country that we do not fully understand in all its states, so it brings us to the all but absolute proof that it is no other than the CEstrus pictus, so called by Curtis in his excellent " British Entomology," and by the continental naturalists. This larva, with others, at different times was received by me by the kind aid of my worthy friend John Bolt, of Lyndhurst, assisted by the kindly interference also of the present forest-keeper and ranger, who desired any larvas found in the killed venison to be brought to him. Any one desirous of seeing a good representation or figure of this species may consult my " Treatise " on this genus, pi. 1, fig. 40, with nearly or quite all the other members in their respective changes of this truly remarkable family.

	Detrudator. � Cuterebra, nigra, holosericea, abdomine glabro cserulescenti nigro, lateribus albo bicingulatis, posticeque rufo. Habitat calidioribus Americes. Ex Museo Dom. Westwood. Yid. fig. 4. Descr. Ceedit maximis hujus generis. Caput obtusum, vertice atro, inter oculos rufum, ore et inferne late album hirsutum. Thorax ater holoseri- ceus, infra insertiones alarum et subtus, albus. Halteres concavae conco- lores, erectse. Alee longiores aurulento-fuliginosa?. Abdomen lsete ceeru- leum ad latera cingulis duobus latis albis, apiceque hirsuto flavescenti rufo. Pedes omnino atri tarsis prselongis articulis sagittato-acutis. Atrox.�Cut. atra, glabra, abdomine ceerulescenti-atro marginibus segmentorum albis. Habitasse creditor in Africa, v. fig. 5. Ex Museo D. Westwood. Descr. Facile inter maximas hujus generis omnino atro ceerulescens, lucidus. Thorax antice scabriusculus, postice glaber. Halteres scutellum circumcingentes, erectae, maxima?. Alee parum puculatse, obscure aurulento, fuliginosee. Abdomen latum, obtusum, incurvatum, atro cseruleum inci- surarum marginibus, albis. Ad latera et subtus albo late conspersum. Pedes atri geniculis tibiarum extus albicantibus.