THE CHEESE FLY 249 



masses of the larvae and pupae of the imported elm 

 leaf beetle; also from a decaying squash. Aldrich in 

 Idaho has reared it from rotting radishes. In Wash- 

 ington it has been reared from human excreta. The 

 complete round of a generation is said to occupy from 

 five to six weeks. (Fig. 25.) 



This fly is one of the dangerous occasional inhab- 

 itants of houses, not only because it may breed in hu- 

 man excreta, but because it is greatly attracted to this 

 substance when it chances to be deposited in the open. 

 There seems to be no especial reason why it should be 

 called the stable fly, since the preferred food habits 

 of its larvae should make it more abundant away from 

 stables, and its scientific name stabidans was given to 

 it by Fallen before its real habits were known. 



It is interesting to note, by the way, that the larva 

 of the fly has been found to have passed through the 

 human stomach, to which it had probably gained en- 

 trance through the eating of spoiled vegetables. 



The Cheese Fly (Piophila casei L.) 



The little, shining-black flies of the genus Piophila 

 breed in cheese, ham, chipped beef, and other fatty or 

 spoiled and decaying animal matter. The eggs hatch 

 into small, white, cylindrical maggots which feed upon 

 the cheese or meat and rapidly reach full growth, at 

 which time they are one-half of an inch in length. The 

 maggot is commonly called the cheese skipper or the 

 ham skipper from its wonderful leaping powers, which 

 it possesses in common with certain other fly larvae, all 



