411 



Family Cuterebridae — The Robust Bot Flies 



Cuterebra sp. 



Flies of large size, the hair very short, sparse except on the thorax; 

 squamae large; metascutellum not at all developed. 



This family differs from the CEstridje in having the scutellum 

 elongate, the i)ostscutellum entirely undeveloped, the arista is usually 

 plumose or pectinate, the form is generally more robust and the body 

 less evidently hairy. In addition the oral opening is larger, sub- 

 triangular (produced in front toward the vibrissal angles) and the 

 palpi are always small. 



The remarks concerning the CEstridse apply fairly well to this 

 family. These flies are, in North America at least, mostly parasitic 

 upon rodents and they have been reared from rabbits, rats, mice and 

 squirrels. The larvae have been found along rabbit runs, but the adults 

 are only infrequently encountered. 



It seems probable that this family is an offshoot of the MetopiidsE 

 type rather than of the Tachinid stock as is evidenced by the absence 

 of the postscutellum and the usually feathered arista. There does not 

 seem to be a close relationshi]) between these insects and the CEstrid* 

 despite the similar habits and reduced moutli parts while the Gastero- 

 philida? are still further removed, coming, as they do, close to the 

 ]\Iuscida?. The Tachinida? having reduced mouth parts have more or 

 less distinct ab<lominal bristles. 



Probably the most unusual habit in the insect world is that of 

 J)i rmatohiii hominis (cj/aniventris) , the human bot fly. The fly lays 

 its eggs on otlua- insects, usually mos(juitoes. and they are carried by 

 the latter to the host. The eggs contain mature first stage larvae and 

 these emerge from the eggs when the carrier begins feeding and pcne- 



