336 Wisconsin State Hobticultuhal Society. 



pupa within its flaxseed skin, the fly emerging from the flax-eed 

 case about the end of April. The eggs laid by this first or spring 

 brood of flies soon hatch; the second brood of maggots live but 

 a few weeks, the flaxseed state is soon undergone, and the autumn 

 or second brood of flies appears in August. In some cases there 

 may be two autumn broods, the earliest August brood giving rise 

 tD a third set of flies in September. The first brood of flies lay 

 their eggs on the leaves of the young wheat from early 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. Thus our crops of winter wheat, as is state 1 by 

 Dr. Fitch, are liable to two attacks of the Hessian Fly, one gen- 

 eration reared at its roots producing another, which occupies the 

 lower joints of the stalks. Thus the larva? and pupa? are present 

 in it almost continually from the time the tender young blades 

 appear above the ground in autumn, till the grain ripens and is 

 harvested the next summer. Our spring wheat, on the other hand, 

 can rear but one brood of these insects; they consequently resort 

 to it but little, if at all. Nor can the Hessian fly sustain itself 

 except in districts where winter wheat is cultivated in which for 

 it to nestle during the autumn and winter." 



The first evidence of their work is the change in color of the 

 wheat, turning from a bright green to a yellow shade, and this 

 appearance is noticed the earliest on the higher ground, where the 

 soil is dryest and light. This has been supposed to indicate that 

 dry weather, as with the chinch bug, is most favorable for their 

 development, while the reverse is true. This is evident from the 

 fact that the year preceding the years when they have been the 

 most destructive have been noted for their excess of moisture, 

 and that they are seen to propagate much more rapidly in a warm, 

 and wet autumn, and even in a cool and moist season than a warm 

 dry one. Where they have full possession of the field early in the 

 spring and in large numbers, the damage done by them in dry 

 seasons is more marked, for the drouth diminishes the amount of 

 nourishment taken up by the plant, and the larva appropriates so 

 much of what there i*, as to leave little or none for the wheat, and 



