CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 261 



Pupa. — Pupa-case translucent pale green; pupa greenish and } e inch 

 long. 



Broods. — Probably three generations occur each season. The 

 eggs are laid in September-October on fall wheat. The maggots 

 eat down into the stem where they remain all winter. In early spring 

 they assume the pupal stage, and about the first of June the adult 

 flies appear. This brood matures 

 about August ist, when flies again 

 appear. This third generation ma- 

 tures at the end of September and 

 the beginning of October, when the 

 adult flies escape to lay their eggs. 

 Besides wheat, rye, barley, and 

 oats, this insect attacks timothy, 

 couch grass, Elymus, Poa, and 

 green foxtail. 



Control. — Grain stacked or 

 threshed; straw stacked or burned; 

 burning of stubble when practicable. 



Meromyza nigriventris Macq. 

 and Cerodontha femoralis Meig. 

 have been recorded as doing injury 

 in Montana. 



American Grass Stem Maggot 

 {Oscinis carbonariaLoew .) . Adult. — 

 A black or yellowish fly, resembling 

 a minute house-fly, ifs inch long. 



Larva. — A yellowish-white 



slender maggot with two distinct p,^ i66.-The wheat stem maggot: 



hook-like jaws and two knob-like a< adult; b, maggot; c, pupa; d, pupa 



,11, . r i.1- within the stem; e, parasite. (After 



processes on the last segment 01 the i^^„„g^ ) 

 body; ^f 2 inch long. 



Pupa. — Pupa- case cigar-shaped and pale chestnut brown. 



Broods. — Similar in life-history to Wheat Stem Maggot. The 

 larva destroys the centre of the young shoot at the ground in the 

 autumn. 



Other Species. — O. coxendix Loew. and 0. dorsala Loew. occur on 

 prairie grasses, sometimes very abundant. 



