DIPTEKA OR TEUE FLIES. 



203 



The Cruoifee Midge (C. brassic2b). 



Another member of the same family is often injurious to 

 turnip and cabbage seed. The larvas of this midge live in the 

 seeds of turnip, rape, and cabbage, in the pods. As many as 

 sixty may often be found in one pod, which they cause to turn 

 prematurely yellow and to burst. The fly has a black head and 

 thorax, pinkish abdomen banded with dark-brown, and black 

 legs which are silvery beneath. The female has a long white 

 ovipositor, and lays her eggs in the young pods. We find the 

 larvse in May and June : they are white, often with a greenish- 

 yellow stripe down the middle. They reach one-twelfth of an 

 inch in length when mature, and fall to the ground out of the 

 split pod and there pupate, coming forth as the second brood of 

 flies a few days hence. I have found it has three broods at 

 times. Little can be done to prevent its damage, which is often 

 severe. 



Numerous other Cecids make their effects felt, but space for- 

 bids our even mentioning them here. 



The Bibionidse form a family of dark flies with broad bodies, 

 short legs, and the tibite armed with thick spines. They 



Fi<!. 97. — BIBIONID.*:. 

 A, Adult liihin marci: B, l.irva and pupa of B. jiomojjcr. 



frequent damp meadows, and some of tlie genus Bihio appear in 

 great numbers. One species, the Fever Fly (^DiJopJuis fehrili^), 



