181 



specimens were scattered, wliile the remainder of the field was tube 

 plowed for wheat within a few days. The fact that specimens of the 

 tSemioteUufi continued to emerge from the check lot retained at Cham- 

 paign for some weeks after this distribution is evidence that a consid- 

 erable number of the parasites must have gone abroad iu Scott County. 

 Indeed, forty or fifty of them, which had completed their transformations 

 en route, escaped from the box when it was opened in the field. 



It will be seen from the foregoing narrative that we succeeded com- 

 pletely in breeding a generation of the foreign parasite in our plots of 

 wheat infested by the Hessian Fly, and that these bred insects were suc- 

 cessfully distributed to fields infested by the fiy at two places in Illi- 

 nois — in Champaign and Scott counties, respectively. 



It should be said in conclusion that the latter part of the summer was 

 exceedingly dry througlumt central Illinois, and that as a consequence 

 but little volunteer grain grew in either of the above localities, and that 

 neither in this nor in the early sown wheat was there any considera- 

 ble amount of Hessian Fly attack — circumstances which are to some 

 extent unfavorable to rapid success of the experiment for the introduc- 

 tion of this parasite. The Yantyle farm was visited by my assistant, 

 Mr. Marten, September 24, at which time the plowed portion of the field 

 was being drilled to wheat. Along the margins of this i>lowed ground, 

 near the plot which had been left in stubble, was a scanty growth of 

 volunteer wheat in which, after considerable search, four nearly full 

 grown larvfe of the Hessian Fly and one fresh pupariuin were found. 

 Little other volunteer wheat was seen in the neighborhood. A brief 

 search of the stubble remaining showed only parasitized puparia from 

 which parasites had already escaped. 



The Champaign County plot was examined September 30, when one 

 hundred and twenty plants of volunteer wheat grown in the experi- 

 mental stubble field were overhauled. In these plants two larvae and 

 seven puparia of the Hessian Fly were found. October 5 from forty- 

 three plants eight puparia and two nearly full-grown larvie were taken. 

 As the period of the emergence of the imported Semiotellus was sub- 

 stantially the same as that of the native *S'. destructor, the two coming 

 out side by side in our breeding cages, it seems practically certain that 

 the imported parasite must have had as fair a chance for propagation 

 in the field as its native congener. 



We will of course keep careful watch of these localities next year, 

 and A\'ill notify you of any observations then made bearing on the reap- 

 l^earance and the spread of this imported enemy of the Hessian Fly. 



To C. V. Riley, 



U. S. Entomologist. 



