172 



THE BOOK OF WHEAT 



larvae is passed in the stubble in the flaxseed stage. In Mich- 

 igan the fall brood appears about the last of August, while in 

 Georgia it appears about 3 months later. The eggs are now 

 deposited on the young fall wheat, and the life cycle begins over 

 again. In regions far north there may be only one brood, 

 and m the south there may be supplemental broods, both in 

 the spring and fall, this being dependent on the weather 

 Drought prolongs the flaxseed stage. 



In the spring wheat regions the insects winter in the flaxseed 



stage, chiefly in stubble, but also in volunteer wheat Egg 



laying begins late in May and continues to October 1st. Eggs 



>ten deposited on grass and weeds, but the larvaj are not 



known to survive except on wheat, barley and rye. The fly 



A B 



HESSIAN FLY: a, ADULT; b, PUPA; c, LARVA. ENLARGED 



is now known to flourish even where spring crops are exclusive- 

 ly grown. 



EFFECT OF LARVAE ON WnEAT.-At first the plant seems to 

 be stimulated, and turns a dark green color. Later the in- 

 fested tillers turn a brownish and then a yellowish color If 

 the attack comes early, and the plant fails to tiller, death re- 

 sults. If the plant has tillered, some stalks may escape and 

 torm the basis for a crop. The larvas are usually found just 

 above the first joint, but may be found from aHove the third 

 joint to below the soil. The stalk is usually so weakened that 

 it breaks to the ground, when the wheat is said to be " straw 

 fallen." 



LOSSES. The Hessian fly is the worst insect enemy of 

 growing wheat. It is never entirely absent. The minimum 



