INSECTS AFFECTING WHEAT. 



INJURING THE STALK AND LEAF. 



The Hessian Fly. 



( 'ecidom.yia destructor. 



This is one of the oldest and best known insect 

 pests of American agriculture. It has ranked as a 

 destructive species for more than a century, and has 

 probably been intro- 

 duced nearly every- 

 where that wheat is 

 grown. The adult is 

 a small, two-winged, 

 m o s q u i t o-like rl y 

 (Fig. 117, d), the fe- 

 males of which de- 

 posit their eggs on 

 the upper surfaces of 

 the wheat blades ear- 

 ly in autumn. In a few days the larvae hatch, and 

 each descends the leaf to the base of the sheath, 

 where it attaches itself, head downwards, to the stalk, 

 and proceeds to absorb the life-sap of the plant, As 

 the latter grows the young larva becomes imbedded 

 in the stalk, where it remains stationary. When 

 full-grown (which occurs in three or four weeks from 

 the time of hatching) the larva is a soft, white, foot- 

 less maggot of the form represented at a. Its outer 



Fig. 117. Hessian Fly: u, larva ; b, pupa; 

 c, injured stem : <l, fly. 



