It was to this species that Linnaeus referred when he wrote the apparent paradox that three FUes could eat an ox as fast as a lion. The Fly does not even wait for decomposition, or at all events can detect incipient decomposition long before it is apparent to the human senses ; for I have often found that if a recently-killed mouse or bird be allowed to lie in any exposed place for an hour or two, vast numbers of these tiny larvae will be deposited upon it, the mother Fly having taken the precaution to place them under the wings, in the mouth, at the

junction of the legs with the body, or, if the creature be lying on the ground, upon the surface of the body that is next to the earth.

This is not the only Fly that deposits its young in this curious manner, but I have selected the best known species as an example of the group.

On Woodcut LXXV., at Figs. 2 and 3, are shown two species of the well-known Dung-Flies, of which the common LXX^

Musce 3. Scatopbaga stercoraria. domGstica, 2, Scatopbaga scybalaria. &. Do., tongue. a. Scatopbaga scybalaria, antenna.

Cow-DUNa Fly {Scatopbaga stercoraria) is the most plentiful. In this genus the last joint of the antenna is rather long, the head is spherical, and the body covered with stiff hairs. These Flies may always be found in fields frequented by cows, as it is upon the dung of these animals that the larvse are fed. The most remarkable point in the economy of these insects IS the development of the egg. It is necessary for the due

batching of the young that the egg should be kept in a state of moisture as well as warmth, and this point is secured by depositing the egg in the recent cow-dung. This, however, is not all. If the egg becomes dry, it shrivels up and the young maggot is never hatched, while, if it should sink entirely, it is drowned, so to speak, the egg requiring air as well as moisture.

This object is attained in a very simple but effective manner. i

egg is shaped something like that of the domestic fowl, The being larger at one end than at the other. At the large end, appendages project from the egg and diverge two horn-like each other, their roots being about one-third of the from of the egg from the upper part, so that the egg cannot length than the horns. When the time comes for the sink deeper the larva, the egg opens at the wide end, and the hatching of through the opening. These eggs may be young grub escapes more than a hundred being stuck into a space found in plenty, a man’s hand. The larva is conical in scarcely wider than being at the apex of the cone, and the broadest shape, the head end being armed with a number of little fleshy points. or tail Cow-dung Fly is too well known to need

The common yellow The other species, Scatophaga scyhalaria, which description. in colom-, but through is shown at Fig. 2, is orange-ochreous hair a number of black bristles protrude. The the soft yellow are brownish, and the first segment of the thorax and scutellum The wings are sHghtly iridescent and abdomen is ashen-grey. margin. The tips ot : inclining to orange on the costal brown, the thighs of the hind legs are black. -^| LXXVI. Fig. 1 is a magnified representation of

On Woodcut In this genus the a little Fly called Phora abdominalis. instead of being long and nearly third ioint of the antennae, The margin of the vnngs is cylindrical, is almost spherical. is given to this species on fringed. The name of abdominalis which is broad at the base account of the form of the abdomen, One of the hind legs is shown at tapers rapidly to the tip.

and of the head is given at I ig. a.

Fiff. h, and a profile view is glossy black, and the head is

The colour of this species The palpi are orange. ^

irregularly and coarsely punctured. rust-red, and the wings .

The thorax is downy, the abdomen

yellowish, with bro'wn nervures. Some of these insects were

hatched from larvae found attached to the pupae of ladybirds.

The larvae of these PTies are found to feed on various

substances, some being believed to be parasitic on other larvae,

and others having been observed to feed on vegetable substances. For example, the larva of one species, Phora dauci,

Do., leg. c. Ormthomyia fringiUaria, leg. d. Do., maxilla. was seen to feed upon the interior of decaying radish-roote. The larva is nearly cylindrical in shape, but is slightly narrowed m front. The last segment of the body has radiating points, like those of the one or two eight larva, which hL se'^et:™ ’ ““ --

We now come to the small but important family of the (Estiidm, popularly known as Bot-Flies. In these inLts the

parts of the mouth are quite undeveloped, the whole of the structures being represented by two or three little tubercles. In the perfect state, therefore, these Flies are quite harmless, hut in their larval condition they are hurtful to various animals. In fact, all our cattle are attacked by these insects, which are parasitic upon or in them, and not even the thickskinned camel and rhinoceros are exempt from them.

One of these insects, the common Bot-flt {Gasterophilua equi) is shown on Plate XX. Fig. 3. Its life history is briefly as follows : —

The mother insect flies about a horse, and with its ovipositor places an egg on the hair of some part which the horse is sure to lick. The egg is thus taken up by the tongue and conveyed into the stomach, where it is hatched. The larva then attaches itself to the inner membrane of the stomach, and appears to feed upon the secretions.

The number of these larvse which will inhabit the stomach of the horse is really wonderful. I have seen the interior of that organ so covered with them that the surface of the stomach was completely hidden by their depending bodies. In form they are nearly cylindrical, but the body is suddenly narrowed towards the head, which is armed with a number of little hooks, by which the grub attaches itself to the interior of the stomach. They remain within the stomach of the horse throughout the winter, and in the spring they are full-fed and loosen their hold of the stomach. They are then carried through the intestines and fall to the ground, into which they at once burrow and there assume their pupal form. The process of transformation lasts about three weeks, and at the expiration of that time the perfect fly appears.

Opinions are greatly divided as to the effect produced on the horse by these larvse. Some of our best authorities, Mr. Youatt among the number, believe that they do no harm, while some go so far as to think that their presence is beneficial. I cannot hut think, however, that as these larvse derive from substances within the stomach of the all their nourishment horse, they must abstract a corresponding amount from the nourishment of the horse, and that, whether they cause inconvenience or not to the animal, their presence must be in some way hurtful to it.

The generic name Gasterophilus is formed from two Greek words, and signifies ‘ belly-loving.’ It has been given to the insect in consequence of the habits of the larvse. It is rather ; a pretty insect, and has some resemblance to an Andrena. The thorax is black, partly covered with warm chestnut down, and the abdomen is alternately banded with ruddy chestnut j and black. The wings are slightly clouded with brown.

There ave several other insects belonging to this family, each of which selects some particular animal for its home.

There is, for example, the Wtieble Breeze-fly, or Gad-fly {(Est't'us bovis), the economy of which is very remarkable, the creature seeming to produce much the same effect upon the ox that the gall-flies do upon plants. Instead of being taken into the stomach of the animal, as is the case with the last-mentioned species, this species never penetrates further than the skin.

Into the skin the larva burrows as soon as hatched, and it is remarkable that the female insect takes as much care to place the egg on the back where the tongue of the ox cannot reach it, as the Bot-fly to place the egg where the tongue of the horse has easy access to it. Beneath, or rather in, the thickness of the skin, the larva makes its residence, its head being ownwards and its wide tail upwards, so as to receive air into

e Wurble, as the grub is called, is made evident by a small which 7bf bTb the ' tail 1 1 end of the larva can be opening through seen. ^

When It IS full-fed, the larva retrogrades out of its habitaon falls to the earth. No sooner is it fairly on the ground than it begins to bm-row, and then undergoes ffs trans formations underground, exactly as has been

y. The stated of the colour of this species is brownish, the base of the chesW. '' is ^'^ddy

Then there is the Sheep-fly {(Estrus ovis), a smaller, and more slender species. The female of • I grever ^ ’ the nostril of the sLep as the ptar th: eon deposit her eggs. The heTstb^^^^^^ sheep are very much afraM msect, and do all in their power to rid themselres of the.' r

enemy, rubbing their noses against the ground, shaking their heads, and rushing about in all directions. Their exertions are, however, useless. Sooner or later, the fly succeeds in depositing her eggs just inside the nostril, and there leaves them. They are soon hatched, and then the young larva, which is furnished with hooked appendages to its head, crawls up the nostril, and fixes itself in the frontal sinus. Its life then much resembles that of the other insects of the family.

Antelopes are known to be specially subject to the attacks of the Grad Fly, and all African hunters say that the head of the gnu is never found to be without at least one Gad I ly grub in the frontal sinus.

now come to the last great division of the Diptera, the or those insects whose heads are sunk in the Thokacocephala, Like the preceding insects, they are all parasitic, but thorax. in many points from them. In the first place, they differ there is the position of the head, to which reference has just been made, and besides, the antennae are differently arranged, mode of transformation is different. In consequence and the it has been thought by several eminent of these peculiarities, insects ought not to be ranked with entomologists that these be constituted into a separate order, to the Diptera, but to was given. It has now, howwhich the name of Homaloptera that they really are Diptera, though they ever, been decided divergent branch of that great order. form a very two families, the first of which is

They are divided into This term is composed of two Greek named Hippoboscidse. a horse, and the latter, to feed words, the former signifying appropriate is the word, anyone can upon. How thoroughly a horse when the Flies are tell who has driven or ridden on foot, and can run sideways as about They are very active among the hair fast as they can forward, burying themselves attack. In some of t e or feathers of the creature which they wanting, as is the case with insects the wings are entirely ovmus). ^ I need verv common Sheep-Tick {^Mdo^hagus is entirely a wrong one, inasmuch scarcely say that the name insect, and the true ticks belong as the Sheep-tick is an This, being very plentifid, a krL class of beings.

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