114 



INSECTS INJURIOUS TO STAPLE CROPS. 



manner. They will not need consideration by the prac- 

 tical farmer other than in applying methods of control as 

 already given. One species of this genus, determined by 

 Prof. H. Garman as Oscinis variabilis Loew and christ- 

 ened the American Frit-fly, has been found common in 

 Kentucky and Canada, but is so nearly identical in 



Fig. 65. — The American Frit-fly (Oscinis virinMlis Loew). a, 

 larva or maggot; b, puparium; c, adult fly. (After Garman.) 



appearance and habit in the larval stage that it can with 

 difficulty be distinguished from the Stem-maggot. 



That these pests do not do more injury is probably due 

 to a considerable extent to the fact that large numbers of 

 them are destroyed by a small hymenopterous parasite, 

 known as CoBlimis meromyzce Forbes, which very commonly 

 infests the larvse, and by other parasites and predaceous 

 insects. 



Rarely will these pests do serious damage, but very often 



