INJURING THE STALK AND LEAF. 221 



skin now becomes hard and brown, and separates 

 from the rest of the body, although it still surrounds 

 the latter, forming a sort of cocoon, or, as it is more 

 correctly called, puparium, within which the insect 

 changes to a pupa (b). This is the " flaxseed " state, 

 so called because of the resemblance of these brown 

 puparia to flaxseeds. The winter is usually passed 

 in this condition, and in spring the flies emerge from 

 the flaxseeds to lay eggs for another brood. The 

 larvae of the fall brood affect the young wheat plants 

 just above the roofs, between the stalk and sheathing 

 base of the leaf, but the spring generation are formed 

 a little higher up, at the joints an inch or more above 

 the soil surface. This second generation completes 

 its transformations before harvest, and there is often, 

 if not always, at least as far north as the latitude of 

 40 degrees, a third brood, which develops during 

 summer in volunteer wheat ; and Professor Fori >es 

 has shown that there may occasionally be even a 

 fourth brood during the year. But the chief damage 

 is done by the fall and spring broods. 



There are several species of insect parasites which 

 attack the Hessian Fly, so checking it that in most 

 localities it only occasionally becomes injurious. 



Remedies. — The most promising method of pre- 

 venting the injuries of this insect appears to be that 

 of inducing the flies to deposit their eggs in young 

 wheat, and then destroying it. Where a third brood 

 develops in volunteer wheat this end may be accom- 

 plished by turning under this volunteer growth 



