32 



CIRCULAR 1 4 



U. S. DEPARTMENT OF AGRICULTURE 



Bots 4 



Bote are maggots of certain flies tig. 22 known as botflies. Three 



species of bots commonly occur in horses in the United States. 



The common botfly. Gasteropkilus \ntestinalw, occurs in practically 

 all parts of the United States. The bots. or parasitic larvae, are reddish 

 in color and are attached to the white covering of the left sac of the 

 stomach or along the ridge between the right and left sacs of the 

 stomach. The adult fly deposits its eggs on the hairs of the inside of 



Figure 22. — Portion of a horse's stomach, showing bots, Gastrophilus iyitestinalis. 

 attached to the inner lining of the stomach wall. Natural size. 



the front legs, breast, mane, belly, and even the hind legs. The throat 

 botfly, or chin fly. G. nasalis, is rather widely distributed in the United 

 States and is especially common in the Rocky Mountain region. The 

 adult fly of this species deposits its eggs under the jaw of the horse, 

 and in so doing causes much annoyance to horses. The bots are yellow- 

 ish in color and are attached to that portion of the stomach which joins 

 the small intestine and also to the wall of the upper part of the intestine. 

 The nose fly, G. hemorrhoidalis, has a more limited distribution than 



1 For more detailed information concerning horse bots and their prevention 

 consult Farmers' Bulletin 1503. The Horse Bots and Their Control. 



