FIELD CROP INSECTS 



251 



discovered on Long Island, in 1779, just where the Hessian 

 troops had landed three years before. It has been esti- 

 mated that it reduces the wheat crop by 10 per cent every 

 year and frequently 25 to 50 per cent is lost in restricted 

 localities. 



The adult flies are small dark-colored gnats about one- 



FIG. 177. The Hessian fly (Mayetiola destructor). (After Marlatt, 

 U. S. Dept. Agr.) 



o, female fly; b, flaxseed stage or pupa; c, larva; d, head and breast-bone of 

 same; e, pupa; /, puparium; g, infested wheat-stem showing emergence of pupa 

 and adults all greatly enlarged. 



tenth of an inch long, so small as commonly to escape obser- 

 vation. The females lay their small reddish eggs usually 

 on the upper surface of the leaves. The maggots hatching 

 from these in the fall burrow beneath the sheath of the leaf 

 at its base, causing a slight enlargement at the point of at- 

 tack. In the spring they usually stop at one of the lower 



