716 NEW YORK STATE MUSEUM 



was sewn late, and in early July many fields in Genesee county 

 were badly infested. Tlie pests were near the ground in. the 

 latest sown barley and in that early sown, they occurred from 

 10 to 12 inches from the ground, showing at least, that the insect 

 breeds by preference in the soft growth and inferentially that 

 it thrives only indifferently in the older, harder growth. This 

 relation between the rank succulent growth of the grain and 

 injury by the Hessian fly was further shown on one hilly patch 

 of wheat. There was considerable grain on the gravelly, com- 

 paratively dry knolls while in the more moist, probably poorly 

 drained gullies the stalks of wheat were very scattered. Here 

 seems to be a possible reason why a variety of wheat may be 

 comparatively " fly proof " in one section and not in another, 

 since its apparent resistance may depend very largely on the 

 relative hardness or maturity of the stalk at the time the flies 

 appear and deposit eggs and this might easily vary in widely 

 separated sections during the same season. Another generation 

 might easily have developed, so far as time is concerned, between 

 the middle or the latter part of July, at which date the above 

 mentioned brood attained its maturity, and the period when the 

 normal fall brood appears, which is usually before September 

 20 in New York. The above shows that four generations and 

 possibly more may develop in a season, but it should be distinctly 

 understood that, as a rule, only two full broods are developed, 

 and that the intermediate summer generations are usually very 

 limited and that their development is very dependent on weather 

 and crop conditions. 



Emergence and flight. This is an exceedingly important mat- 

 ter, because on its correct understanding rests one of the most 

 successful methods of preventing injury by this pest. This, 

 like the development of the summer generations, is dependent 

 on weather conditions. The following rules will aid in under- 

 standing the situation: 



1 The flies may remain an indefinite period in the " flaxseed " 

 or pupal stage during dry weather. 



2 " Flaxseeds " or pupae are very likely to develop dies in 

 large numbers during a period of damp, warm weather. 



