CEREAL PESTS INSECTS 473 



The chief food plant of the Hessian fly is wheat. It is 

 found also on barley, but does not develop well on rye 

 and does not attack oats at all. It is known also to breed 

 in several species of wheat-grass (Agropyron repens, A. 

 tenerum, and A. Smithii). 



The eggs are generally placed in the grooves of the 

 upper surface of the leaves, though occasionally found on 

 the under side of the leaf. The young larva as soon as 

 hatched makes its way down the leaf and inside the 

 sheath. The fall generation of larvae 

 is found just above the roots of the 

 seedling plant, except in cases where 

 the latter has become disintegrated 

 and separated at the place of attack 

 in the fall, or the plants have been 

 heaved out by the alternate freezing 

 and thawing, in which case the larvae 

 may be scattered about on the ground. 



r J , , .!, FIG. 149. Pupa of 



1 he larva occurs on the plant with its the Hessian fly, 

 head downward, but later turns its called the flaxseed 

 head upward in the flaxseed. 



518. Life-history of the Hessian fly. There are two 

 generations of the Hessian fly, probably in all parts of the 

 United States, at least in favorable seasons. In the South 

 the two generations are most widely separated, while in 

 the spring wheat districts of the North, one apparently 

 follows the other in quick succession. 



In winter wheat districts the fly passes the winter in 

 the young wheat, usually in the flaxseed stage; also, 

 perhaps, in the South, as larvee f to full grown. In the 

 spring the adult flies escape from the flaxseeds, in March 

 in Georgia and South Carolina and in May in Michigan, 

 and deposit their eggs on the wheat, the young from which 



