39 



Our observations were directed almost wholly to the midsunimer 

 history of the insect, the facts respecting its autumnal injuries and 

 its hibernation being sufficiently well settled. As a fair example of 

 the current view of the summer history, we may take the following 

 account from Packard's "Guide to the Study of Insects": 



"The flies appear just as the wheat is coming up; they lay their 

 eggs for a period of three weeks, and then entirely disappear. The 

 maggots hatched from these eggs take the flaxseed form in June 

 and July, and are thus found in the harvest time, most of them 

 remaining on the stubble. Most of the flies appear in the autumn, 

 but others remain in the puparium until the following spring. By 

 burning the stubble in the fall, their attacks may best be prevented." 



It will be seen, however, from the observations here reported, that 

 the above history is inaccurate for Southern Illinois, and that the 

 remedy mentioned by the author is, as a consequence, to a great 

 extent inapplicable.* 



In following the life history of the fly through the season by means 

 of breeding experiments and field observations and collections, the 

 principal embarrassment has arisen from the immense prevalence 

 of parasitism in the summer brood, so that breeding cages contain- 

 ing hordes of the larvie and flaxseeds would yield scarcely a single 

 fly, and fields in which they had destroyed the crop would send forth 

 so few of the adult insects that the most diligent sweeping at the 

 season of their emergence would not obtain a single specimen. 



LIFE HISTORY. 



1883. 



Our observations for 1883 began at Centralia, April 10, at the 

 time when the Hessian Hy was abundant in the pupa state, and 

 was also rapidly emerging in the winged form. From a large num- 

 ber of wheat plants containing the flaxseeds sent to Normal at this 

 time, flies continued to emerge until the 20th of the month, after 

 which no more appeared. These imagos laid their eggs in the 

 breeding cages almost from the first. 



On the 5th of May young larvae of the spring brood were collected 

 at DuQuoin, some of them scarcely more than hatched, and others 

 full grown. These were placed in a closed fruit jar in a room ad- 

 joining the office at Normal, and kept under cover at the ordinary 

 temperature of the out-door air; and to my surprise, on the 28th 

 of May, two imagos appeared in the jar. Upon June 4, four more 

 emerged, three males and one female, and others at intervals until 

 June 15. 



On the 17th of May, examples of both free larvae and flaxseeds 

 were received from Odin, in Marion county. On the 24th, we col- 

 lected larvae only, from wheat fields in Decatur, in Macon county, 



* It is but fair to state that in his later papers Dr. Packard revokes the recommenda- 

 tion quoted above, for the burning of stubble in fall, and describes it on the contrary as a 

 measure likely to be productive of the greatest harm; but not on the ground that the 

 flaxseeds, which it is intended to destroy, have most of them given exit to the fly, but 

 rather on ground which seems to me wholly untenable, viz: that the harm done by the 

 destruction of the parasites must far overbalance the benefit done by burning the 

 flaxseeds in the field. 



