INSECTS INJURIOUS TO SMALL GRAINS 



131 



to the pupa. The fly is 

 It is of a yellowish-white 



larvae are a light greenish color, about one-fourth of an inch long 

 tapering toward the terminal end while subcylindrical posteriorly, 

 being quite elongate. The pupae are the same color as the larvae, 

 but more rounded, being only one-sixth of an inch long, and reveal 

 the legs and wing-cases of the imago forming within them. The 

 external case of the pupa, called the puparium, is merely the 

 shrunken and hardened cast skin of the last larval stage, 

 within which the insect transforms 

 about one-fifth of an inch long, 

 color with a black 



" 



spot on the top of the 

 head, three broad 

 black stripes on the 

 thorax, and three on 

 the abdomen, which 

 are often interrupted 

 at the sutures, so 

 that they form dis- 

 tinct spots. The 

 eyes are a bright 

 green. 



The winter is pass- 

 ed by the larvae in the 

 young plants and in 

 spring they trans- 

 form to pupae and 



j ix a' T-U FIG. 112. Wheat bulb-worm (Meromyza ameri- 



adult flies. These in mn?): a> mature fly . 6> larva . c> puparium; 



turn deposit eggs in d, infested wheat-stemall enlarged except d. 



(After Marlatt, U. S. Dept. Agr.) 

 such a position that 



the maggots issuing from them may readily feed upon the succulent 

 portions of the growing stalk. Numerous larvae thus sapping the 

 life of the plant soon kill it outright or cause the top and head to 

 wither and die. The adults of this brood emerge in July and lay 

 eggs on volunteer wheat and grasses, the maggots working in the 

 same manner as in the fall and coming to maturity so that 

 another brood of flies lays eggs for the fall brood on the newly 

 planted wheat. 



Owing to the fact that this insect breeds also in grasses dur- 

 ing late summer it is much more difficult to combat than were it 

 confined to wheat as its food-plant, as is the Hessian fly. 



