BOT, BOT-PLY, and names common to many insects of the family satritke (q.v.)or cestracidtr, the genus (estrus of Lirinmus. The name bot is Sometimes restricted to the larva!, which appears to have been its original use, the other names being given to the perfect insects; the 11:iMe gadtly often to insects of the genus tabanua (q.v.), to which some try to restrict it. The insects of this family are now supposed not to he those which were called erstras by the ancients. :ilthotigh, like them, extremely trouble some to cattle. They are dipterous (two-winged) (q.v.) insects, nearly allied to the atuseidas (house-fly, fiesh-tly, blow-tly, etc.), with small 3-jointed antenna, and mouth destitute of a proboscis.—'rlie horse-bot, or gad-fly of the horse (awake/Ai/cm, or pragrua, nr estrus epee), sometimes also called the breeze, and leurse-lx-e, is much less common in Britain than in some parts of the continent of Europe, and occurs chiefly in elevated healthy districts. It is not quite half an inch in length, woolly. with yellowish gray Lead, rusty thorax, abdomen, and the wings whitish, with brownish-gray spots. The abdomen of the female terminates in a 'thickish homy tube. In the latter part of summer, the female hovers about horses, and deposits her eggs on their Lairs, where they remain attached by a glutinous substance until they, or the larvae just emerging from them, are licked off by the. tongue of the horse, their destined place being its stomach. It is believed that the fly deposits her ergs only ou those parts which are accessible to the horse's tongue, seeming to prefer the back of the knee-joint, where they may sometimes be found in 11rnirctLs. The larva is yellowish, without feet, short, thick, soft, composed of rings a•hich have a double row of short teeth surroundhar them; it is somewhat acuminated at one end—the head; and the mouth is furnished with two hooks, one on each side, for taking e. hold of the inner coat of the lior-ti's stomach, to which the B. attaches itself, and from which it derives its subsistence• hanging in clusters sometimes of three or four, sometimes of more than ono hundred. Ilerc it spends the winter, and in the following summer, when it is about au loch long, it disengages itself, and being carried through the horse's intestines, burrows in the ground; and changes into an oval black papa with spiny rings, from which, in a few weeks, the perfect insect comes forth. Multitudes, of course, hccome the prey of birds, before they can accomplish their hurrowing.—It has been disputed whether or not hots are very injurious to horses; and some have even maintained that, when not excessively numerous, their presence is rather beneficial, an opinion which is certainly not recom mended by its apparent probability, whilst it seems to he universally admitted, that in great numbers they are hurtful.—The red-tailed horse-bot (G. or W. lorenorrhoilialim), also a British species, deposits its eggs upon the lips of the horse, distressing it very much by the anuoyanc,a which it gives in so doing. The larvae attach themselves chiefly to the surface of the intestine, about the anus of the horse, and sonietimes cause au annoying irritation. Linseed oil is used for their removal.—The Ox-BOT, or ox gad-fiy (watecia or leypodcrena Loris) is more troublesome than any species of horse-bot. It is a beautiful insect, not quite half an inch long, and thicker in proportion than the horse hots; it has brown unspotted wings; the face whitish, the crown of the head brown, the thorax black, the abdomen whitish, with a broad black band around the middle, and yellow liairs at the extremity, where also the female has an ovipositor—a remarkable organ, formed of a horny substance, and consisting of four tubes retractile within one another, like the pieces of a telescope; and the last of them terminating in five pointy three of which are longer than the others. and hooked. By means of this organ, a small
round hole is pierced in the hide of an ox's back, in which an egg is depositjd. The tly is very quick in depositing her egg, not remaining upon the back of the animal more than a few seconds. Cattle exhibit great alarm and excitement at the presence of the 4-aci-tly, and rush wildly about. with head stretched forward. and tail stuck mu, to escape from their tormentor. The further injury (lone by this insect is not, however. usually great; the larva—a little pearl whitemaz, rot (erar6le or wormal)—feeding upon the juices beneath the skin, causes a swelling, called a warble, forming a sort of sac. within which it lives and grows, amidst a kind of purulent matter suited to its appetite: and from which it finally timerycis, leaving a small sore, and like the horse-bot, muter aoes its further transformations in the ground. 13y pressure on the warbles. faits may be destroyed. and when they are numerous, assiduous oiling of the back of the ox is resorted to for the Faille purpose.—The S1IEEP-130T (oepl eleneyen or cestrua ores) is it much more serious pest than any other British species, and is not unfrequently very destruc tive to flocks. The insect is smaller than either the ox-bot or horse-hot; it is of grayish color, with a large head and yellow face, and is most abundant in damp situationsand woody districts. It is to be seen chiefly in the months of June and July. Sheep exhibit great alarm when it approaches them, and seem to seek. by keeping their noses close to the ground, and by incessant motion of their fut, to keep it front entering their nostrils. It is inthe nostrils of the sheep that this fly deposits its eggs. and the larva., when hatched, make their way into the maxillary and frontal sinuses, feeding upon the juices there, until they arc ready to change into the pupa state, in April or May of the follow ing year, when they find their way marlin the nostrils to the ground. They seem to cause ,mat irritation in their progress lip the nostrils of the sheep. and the poor ani mals run hither and thither, snorting and in great excitement, "The cominou saying.. that a whimsical person is inaaaae(y. or 'tags got maggots in his lovfl, perhaps from the freaks the sheep have been ohseraaid to exhibit when infested by their hots. The hots cause considerable irritation in the cavities, where they usually fix themselves, and sometimes get into the hratu, and daat1L—Thesa ]arv:e move with considerable quickness, holding on by the hooks with which their mouth is furnished, and contract ing and elongating the body. It is said that flocks fed where broom is in flower are never infe.sted with them; and when many cases arise in a flock, it is found particularly advantageous to remove it to a dry soil.—Goats, deer, and other quadrupeds are also liable to be assailed by different kinds of gad-fly. The eggs of one of the species which attacks the fallow-deer, are deposited in the nostrils, and the larva; make their way in large numbers to a cavity near the pharynx. Reindeer are excessively tormented by these insects, one kind depositing its eggs in their nostrils, and another in their skin; and it is no infrequent thing for a large part of a flock to be destroyed by them. When feeding where bot-flies are numerous, they keep such watch against them, that neglect to eat, become emaciated, and often actually perish in consequence.—Even human beings have sometimes been afflicted by insects of this family. Humboldt saw Indians in South America having the abdomen covered with tumors produced by their larval.