BOT. 



571 



found under bark, in which they form cylindrical 

 burrows, but they have never been observed to 

 produce such mischief as the Scot y tides. 



BOT. The ordinary name by which the grubs or 

 lars -IE of certain species of dipterous insects, belonging 

 to the family CEstrid<.c, or Breeze-flies, are known. 

 The insects of this family are parasitic upon various 

 quadrupeds, the larvus residing and attaining their 

 full growth within the bodies of these animals, in- 

 flicting great pain by their continued attacks ; and 

 it is to be observed, that it is more especially those 

 animals, which, from their domestication, have become 

 of essential service to mankind that are infested, the 

 cow, the sheep, and the horse, being in a more par- 

 ticular manner subject to these tormenting scourges, 

 which change the little comfort which these useful 

 slaves might enjoy during the summer months into 

 perpetual torment. Considerable variation exists in 

 the habits of the different species ; we shall therefore 

 here restrict ourselves to those which attack the 

 horse, and to which the term bot is generally con- 

 fined, the larvae of the species which prey upon the 

 oxen and sheep being termed worbles, or wormalls. 

 The history of those insects lias been treated upon 

 by several authors, VaUisnim, Fischer, Reaumur, 

 Linnaeus, c., but more especially by Mr. Bracy 

 Clark, F.L.S., whose Memoir, contained in the third 

 volume of the Linnaian Transactions (and which was 

 subsequently published separately, with additions, 

 under the title, " An Essay on the Bots of Horses 

 and other Animals ;" London, 1815, 4to.), has left 

 little to be desired concerning the habits and economy 

 of the different species. This gentleman (to whom 

 the author of the present article is indebted for a series 

 of specimens of these insects) was enabled, by tracing 

 the flics through their various stages, to correct a 

 curious error into which Linna'us had fallen respecting 

 them. In the Systema Xatune of the latter author, 

 we iind a species named CEatrus Bavin, but the de- 

 scription attached thereto is that of an insect which 

 attacks the horses, whilst the habit of the species is 

 given " Habitat in ventriculo equorum, in bourn 

 dorso ;" (Vol. II., p. 9(if). edit. 12.) Thus it is evi- 

 dent that this distinguished author was entirely 

 ignorant of the real (Estnis Bovis, and that the 

 accounts which he had heard of that insect residing 

 in the backs of oxen were considered by him to 

 belong to the same species which he had also ascer- 

 tained to reside in the stomachs of horses, "which," 

 as Mr. Clark observes, "certainly never happens." 

 If we, therefore, find such high authority as Linnaeus 

 stumbling over the habits and names of insects pos- 

 sessing, such considerable claims to our interest, it is 

 not perhaps to be wondered at, that the ignorant 

 should equally fall into errors respecting them. Thus 

 Bluadeville, who wrote upon farriery in the reign of 

 Queen Elizabeth, seems to have confused two dif- 

 ferent kinds of larvae in his observation, The 

 second sort of worms have great heads and small 

 long tails, like a needle, and be called hots ; the third 

 sort be short and thick, like the end of a man's little 

 ringer" (which we shall subsequently perceive must 

 be our hots), "and be called truncheons." Dr. John- 

 son gives the ascaridcs as synonymous with bots ; 

 whilst we find Shakspeare furnishing proof of the 

 vulgar opinion current in his times, that these animals 

 were produced from no other source than poorness 

 of condition, an opinion resulting from the old and 

 groundless doctrines of equivocal generation, which 



we have more than once alluded to. The ostler at 

 Rochester, in King Henry the IVth, says, " Pease 

 and beans are as dank here as a dog, and that is the 

 next way to give poor jades the bots." That half- 

 starved beasts must be more tormented by the half- 

 starved bots in their stomachs endeavouring to obtain 

 more food, is not improbable, and would render the 

 poor jades still more jaded ; but that poverty, or bad 

 food, would of itself produce these bots, is an assertion 

 which we hope few at the present day would be cre- 

 dulous enough to believe ; since, although it is un- 

 questionable that the generation of intestinal worms 

 has always been a source of great difficulty, it is 

 equally unquestionable that the bots arise from eggs 

 deposited by a parent fly. Of these flies there are 

 not fewer than rive distinct species which are para- 

 sitic upon the horse. 1. Gastcrophilus Equi; '2. 

 G. luemorrhoidalis ; ;3. G. naxalis ; 4. G. salutifcrits ; 

 and 5. G. Clarkii. These insects have much the 

 appearance of drone flies ; they ily with great velo- 

 city, and make a considerable humming noise during 

 flight. The instinct which they exhibit in selecting 

 a proper place for their oggs is not exceeded, in 

 interest by any other insect. Of this, as exhibited 

 by the Gatteropiiiltu equi, the author of this article 



Gasterophilus equi. 



was a witness, in a meadow near Gloucester. We 

 observed a large-sized rly hovering near a couple of 

 horses, and having selected one of them, she ap- 

 proached it, still on the wing, her body being carried 

 nearly upright in the air, with its extremity consider- 

 ably elongated into a horny tube, which is extended 

 nearly horizontally, and consequently nearly at right 

 angles with the body. This fly chose the side and 

 back part of the shoulder as her place of oviposition, 

 but the inside of the knee and the extreme ends of 

 the hairs of the mane are more generally selected, 

 especially the former. Being anxious to capture this 

 fly, we approached the horses, which had not exhi- 

 bited the least signs of alarm ; but our approach dis- 

 turbed them, and away they scampered. We, how- 

 ever, followed them, as they happened to take the 

 direction in which we were going, and were not a 

 little surprised to see that the parent fly, in her 

 anxiety to place her eggs in a fitting station, had kept 

 up with them, and which she continued to do for a 

 considerable time, during which we drove these horses 

 about the field. The mode in which the egg itself is 

 deposited by the parent fly is thus described by Mr. 

 Clark : " Suspending herself before the part w here 

 she designs to deposit her egg for a few seconds, she 

 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 pro- 

 jected point of the abdomen ; the egg is made to 

 adhere by means of a glutinous liquor secreted with 

 it. She then leaves the horse at a small distance, and 



