192 



ENTOMOLOGY. 



hollow, are rendered solid, hard, and brittle, so that the 

 straw above the diseased part is impoverished and seldom 

 produces any grain. 



REMEDY. Burn the stubble in the autumn or early spring for 

 several years in succession. 



FIG. 236. The joint-worm fly. a, c, e, female; b, d, /, male. After Riley. 



The Hessian Fly (Cecidomyia destructor Say). Two or 

 three small, reddish-white maggots embedded in the crown 

 of the roots or just above the lower joint cause the stalks 

 and leaves of wheat to wither and die; the maggots harden, 

 turn brown, then resemble flaxseed, and finally change into 

 little black midges with smoky wings, which lay from 

 twenty to thirty eggs in a crease in the leaf of the young 

 plant. 



There are two broods of the fly, the first laying their 

 eggs on the leaves of the young wheat from early in April 

 till the end of May, the time varying with the latitude and 

 weather; the second brood appearing during August and 

 the early part of September, and laying about thirty eggs 

 on the leaves of the young winter wheat. 



The eggs hatch in about four days after they are laid. 

 Several of the maggots or larvae make their way down to the 



