i!00 STOMACH BOTS. 



may render bots far more abundant in warm climates, such 

 as the Italian, than in England. 



" The larvae of the bots remain in the horse's stomach all 

 winter, and in the ensuing summer, when the time for their 

 exit arrives, they are from time to time seen firmly attached 

 by their hooks to the horse's anus. Being of a dark colour, 

 they are rarely observed on the fasces or ground, and even 

 when I have had several young horses in my stable, I rarely 

 could see bots unless adherent to the rectum and close to or 

 upon the anus. The larva in this situation possesses little 

 power of motion, and has a tough shell-like appearance, but 

 exposure to atmospheric air seems very soon to excite it to 

 move ; it is, however, endowed with active locomotive power 

 only for a short time, probably only for the day of its exit, 

 so as to afford it means to attain a secure hiding-place in a 

 bank or other favourable retreat. The adhering to the anus 

 would seem to be a natural and habitual act, destined to 

 allow time for the development of the faculty to creep. I 

 have seen the grub on the floor of a stable moving towards 

 the side so rapidly, and with such an outstretched appearance, 

 that at first sight it could not be identified. 



" The bot is next found in the form of chrysalis, the skin 

 becoming shell-like, and retaining the shape and form of the 

 grub as it issues from the horse's intestines, only acquiring a 

 reddish-brown colour. The further metamorphosis in the 

 state of chrysalis is completed by the eighteenth or nineteenth 

 day. I allow one day of latitude, though I believe that 

 there is a definite and constant period which, however, it is 

 difficult to perceive, from the uncertainty of collecting all the 

 larvse in the same condition. The fly escapes from the tough 

 brown shell at the narrow end representing the head of the 

 bot, and it invariably issues fully formed, active and power- 

 ful on wings and legs, and covered with down at an early 



