FAMILY OESTRIDM 



267 



others like bees, and the rat-tailed species {EriMcdls tcnax) 

 looks like a drone bee. 



Bot Flies (Oestridcr). — The hot flies are parasitic in various 

 mammals, occupying the body tissues and primarily the ali- 

 mentary tract. The adults are bee-like, with rounded heads 

 and small eyes, and are hairy. The antennne are sunken into 

 little pockets or pits in the front of the head, and the mouth 

 parts are aborted. The adults do not feed. The females are 



Fig. 213. — Horse bot fly (Gastrophilus equi): a, egg, enlarged; b, nat- 

 ural size; c, larva, newly hatched, enlarged; d, more enlarged: e. oral 

 hooks; /, body spines; fir, mature larva, twice natural size; h, adult female. 

 (Author's illustration. Bur. Ent., U. S. Dept. Ag.) 



the more commonly seen and they deposit their eggs on the ani- 

 mals that are to serve as hosts for the larvte. The males gener- 

 ally remain in shady places among grass, etc., so that they are 

 much less likely to be observed. The larvje seem to have 

 adjusted themselves to the parasitic condition from a more 

 primitive condition, possibly that of living in organic matter 

 of some kind. It seems most likely that some form with 

 habits perhaps like the blow fly might in some cases deposit 



