NATURAL HISTORY. 



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back part of the shoulder. and less 

 frequently on the extreme ends of 

 the mane. But it is a fact v.orthy 

 of attention, that the fly does not 

 place them promiscuously about 

 the body, hut constantly on those 

 parts which are most liable to be 

 licked with the tongue ; and the 

 ova, therefore, are always scru- 

 pnlously placed within its reach. 

 The eggs thus deposited, I at first 

 supposed were loosened from the 

 hairs by the moisture of the tongue, 

 aided hy its roughness, and were 

 conveyed to the stomach, where 

 they were hatched ; but on more 

 minute search, I do not find this 

 to be the case, or at least only by. 

 accident; for when they have re- 

 mained on the hairs four or five 

 days, they become ripe, after 

 which time the slightest applica- 

 tion of Avarmth and moisture is 

 sufficient to bring forth, in an in- 

 stant, the latent lava. 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 moistsurfaceof the 

 tongue, and is from thence convey- 

 ed, with the food, to the stomach. 

 ]f the egg itself be taken up by 

 accident, it n)ay pass on to the in- 

 testinal 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, with a pair 

 «*f scissars, clipped olf some hairs 

 with eggs on tliiMii, from the horse, 

 and on placing them in the hand, 

 moistened with saliva, they have 

 hatched in a few seconds. At 

 other times, when not perfectly 

 ri|)e, the larva would not appear, 

 though held iii the hand, under the 



" same circumstances, for several 

 " hours; a sufficient proof that the 

 " eggs themselves are not conveyed 

 " to the stomach. It is fortunate 

 '' for the animals infested by these 

 " insects, that their numbers are li- 

 " mited by the hazards they are ex- 

 " posi'd to. I should suspect near 

 " a hundred are lost, for one that 

 " arrives at the perfect state of a 

 " fly.. The eggs, in the first place, 

 " when ripe, often hatch of them- 

 " selves, and the larva, wilHiout a 

 "nidus, crawls about till it dies ; 

 " others are washed olf by the wa^er, 

 " or are hatched by the sun and 

 *' moisture thus applied together. 

 " When 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 the 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 cruslied to death, or of 

 " being picked up by the birds who 

 " so constantly, torfood, attend the 

 " footsteps of the cattle. Such are 

 " the contingencies by which nature 

 " has wisely prevented the too great 

 *' increase of their numbers, and the 

 " total destruction of the animals 

 " they feed on. I have once seen 

 " the larva of this oestrus, in the 

 " stomach of an ass; indeed there 

 " is little reason to doubt their ex- 

 " istence in the stomaciis of all this 

 " tribe of animals." 



" 'Ihcso larva," attach themselves 

 " to every part of the stomach, but 

 " are generally most numerous 

 " about the pyliirus, and are somo- 

 '* times, though much less frequtnt- 

 " ly, found in tiu; intestines. Their 



numbers 



