REPORT OF THE STATE ENTOMOLOGIST T9T2 37 



to be somewhat more seriously damaged than others. Mr Henry 

 D. Flach, of Attica, reports considerable damage in that section of 

 the county though not all fields were injured; the loss in some 

 amounted to 30 per cent. 



Food plants. The Hessian fly was early recognized as a pest 

 of wheat, rye and barley, and despite the fact that there are occa- 

 sional records of its occurrence in timothy and other grasses and 

 grains, there is no authentic evidence of its living in anything else 

 except the grains named above and quack or witch-grass, A g r o - 

 pyron repens. This restriction in food plants is of consid- 

 erable importance, since it materially simplifies the problem of 

 control. 



Life history. There are two generations in this latitude norm- 

 ally, though supplemental ones may occur. The adult fly deposits 

 from 100 to 150 eggs, according to Marchal, placing them between 

 the ridges on the upper surface of the blades of young wheat. 

 Midges of the spring brood occasionally thrust their eggs beneath 

 the sheaths of the lower leaves. 



The flies may occur any time after wheat is up and possibly 

 betzveen killing frosts. The eggs hatch in about four days and 

 the maggots then make their way down the leaf to the base of 

 the sheath. They do not burrow but lie next the stem and 

 absorb nourishment from the adjacent soft tissues which gradually 

 become depressed and give way as the insect develops. The mag- 

 gots are usually found in the fall close to the roots of winter wheat 

 and at or beneath the surface of the soil, while in the spring they 

 are more common about the second or third joints. The larval 

 transformations occupy about twenty days, though their duration 

 is much affected by weather conditions. The length of the pupal 

 stage is exceedingly variable and greatly modified by the precipita- 

 tion. Cold or heat and dryness tend to lengthen, and heat and 

 moisture to shorten the duration of the different stages, especially 

 the pupal. The winter is passed in the flaxseed or pupal stage, 

 the spring brood of flies emerge in April or May and in turn de- 

 posit eggs on the more luxuriant leaves and another life cycle may 

 be completed in about thirty days. 



Number of generations. The short life cycle permits a number 

 of broods in one season and apparently there may be as many 

 generations as weather and food conditions permit. We may ex- 

 pect constant breeding during the growing season if continued damp 



