C30 INSECTA. 



Pe/^cof^ra, rioff., is unknown to me, but is at once distinp:uished from all ivitli tlie antcnnce shorter than the 

 head, by the short, thick seta of the antennse. 



The sucker of all the other Athericiras is only composed of t^vo ^ttc, of "vvhich the upper represents 

 the labrum, and the lower the tongue. 



These Athericera; form three small tribes, which correspond with the genera (Estrus and Conops 

 of Linnaeus, and with that o( Musca of Fabricius, as at first proposed by liim. 



As Sfomoi'ys and Bucentes are connected with the last of these genera, we shall commence with the 

 tribe OilsTRiDES, LatreiUe, which is composed of the genus 



QjlsTRUs, Linn., — ■ 

 Well characterised by possessing, in the place of a mouth, only three tubercles, or but slight rudiment.s 

 of a proboscis and paljii. 



These insects have the appearance of large meat-Hies, very hairy, their hairs being generally coloured 

 in rings, hke lUnnble-bees. Their antennEe are very short, each inserted in an excavation below the 

 forehead, and terminated by a rounded palette, bearing on its back, near the base, a simple seta ; the 

 wings are generally apart ; the alulets large, and hiding the balancers ; the tarsi are terminated Ijy two 

 ungues, and two pulviUi. 



These insects are found but rarely in the perfect state, the time of their appearance l;cing very 

 limited. As they deposit their eggs on the bodies of various herbivorous quadrupeds, it is in woods 

 and pastures frequented by these animals that they are to be sought afier. Each species of CEstrus is 

 ordinarily parasitic upon a single mammiferous animal, selecting, as the situation for its eggs, that part 

 of tlie body which is best fitted for the larvai, which either remain in that particular situation, or are 

 passed from thence to a more favourable place of developement. The Ox, Horse, Ass, Rein-deer, Stag, 

 Antelope, Camel, Sheep, and Hare, are the only quadrupeds hitherto known to be subject to the 

 presence of the larvae of ffistri. These animals appear to have a strange dread of the insect, when it 

 seeks to lay its eggs upon them. 



The nature of the abode of these larvae is of three kinds, which may be distinguished as cutaneous, 

 cervical, or gastric, according as they reside either in tumours formed in the skin, or in some parts of 

 the head or stomach of the animal destined to support them. The eggs, whence the larva: of the first 

 kind are hatched, are placed by the parent fly beneath the skin [of oxen, &c.], wliich it [is stated by 

 some authors, including LatreiUe, but evidently erroneously,] to pierce with its ovipositor, composed of 

 four tubes, entering into one another, and armed at the tip with two hooks, and two other pieces ; this 

 instrument is formed of the terminal segments of the abdomen. These larvae, called farms by the 

 French peasantry [and worbles or imrnils by the English], have no need to change their situation, 

 finding themselves, as soon as b(M ii [or rather as soon as they have buried beneath the skin], in the 

 midst of a purulent humour, which serves them for nourishment. The eggs of the other species are 

 merely stuck upon various parts of the body, either close to natural and internal cavities, into which 

 the larvae easily penetrate, and there fix themselves, or wlicre the animal is in the lialiit of licking itself, 

 whereby the larva? are carried by the tongue into the mouth, and so pass to the jilace [in the stotnach] 

 destined to receive them. It is thus that (he Sheep Bot-fly places its eggs at the inner edge of the 

 nostrils of that qmadruiied, wliich becomes agitated, stanjps (he ground ^^ith its fore feet, and hurries 

 away with its head to the ground ; the larva insinuates itself into the maxiUarv and frontal sinuses, 

 and fixes itself to the internal (uembrane with which they are lined, by means of two strong hooks 

 with which its mouth is armed. It is thus, .also, that the Horse Bot-fly deposits its eggs, without 

 settling, by hovering in the air at intervals over the inner part of the legs, at the siilcs of the shoulders, 

 and sometimes on the withers. (Estnts hremorrhoidahs, the larva of which also lives in the stomach of 

 the Horse, places its eggs upon the lips ; the larva;, attaching themselves to the tongue, pass bv the 

 oesophagus into the stomach, where they subsist on the humour secreted by its inner membrane. Thev 

 are generally found round the pylorus, and rarely in the intestines. They often exist in great numbers, 

 hanging like a bunch of grapes ; Mr. Clark, nevertheless, considers that they are rather serviceable than 

 otherwise to the Horse. 



These larvffi have, in general, a conical form, and are destitute of legs. Their body is composed of 

 eleven segments, exclusive of the head, furnished with small tubercles and spines, often arranged in 

 bands, and which facilitate their progression. The principal organs of respiration are situated in a 



