134 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



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 to the pupa. The fly is 

 about one-fifth of an inch long. It is of a yellowish-white 

 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 distinct spots. 



The eyes are a bright 

 green. 



The winter is passed 

 by the larva? in the 

 young plants and in 

 spring they transform 

 to pupsc and adult 

 flies. These in turn 

 deposit eggs in such a 

 position that the mag- 

 gots issuing from them 

 may readily feed upon 

 the succulent portions 



FIG. 97. The American frit-fly (Oscinis variabilis 

 Loew): a, larva or maggot; 6, puparium; c, 

 adult fly. (After Garman.) 



of the growing stalk. 

 Numerous larvs thus 

 sapping the life of the 

 plant soon kill it out- 

 right 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. 



Remedies. " If the grain is stacked or threshed and the 

 straw stacked or burned," says Professor Webster, " it is clear that 



