22 



freely in volunteer wheat at a date earlier than its usual breed- 

 ing season in wheat of the regular sowings; and that the greater 

 part of this midsummer generation emerge as winged flies before 

 winter and lay their eggs immediately, thus giying origin to a 

 third brood which hibernates chiefly in the puparium. In some 

 instances, however, they pass the winter in various degrees of 

 advancement, from the recently hatched larvse to the fully formed 

 semi-pupa. In the experiments on which the latter statements 

 are based, the individuals of this third brood came to maturity 

 in spring a little later than those of the usual fall brood, many of 

 the pupae being fully formed April 15, and the imagos commencing 

 to emerge April 24. - 



Concerning the early transformation to the imago, of naked 

 larvae and recent "flaxseeds" (puparia) found in the wheat late in 

 spring — from May onwards — I have only to add here to the data 

 given in the 14th Report the following item derived from our 

 collections of 1886. A lot of full grown larvse with a few recent 

 puparia collected from growing wheat in Lawrence county May 

 15, commenced to emerge on the 28th May* and continued to ap- 

 pear as winged flies until the 17th June. The history of the 

 field in which this collection was made is peculiar and will be 

 referred to later. It is further worthy of note that puparia ob- 

 tained by me from the wheat at Edgewood, June 17, yielded a 

 few imagos July 5. 



Most of our observations and experiments for the present year 

 were especially directed to a determination of the dates of the 

 occurrence, in volunteer wheat, of the different stages of the in- 

 sect, and to the mode of hibernation of the descendants of the 

 midsummer brood. 



IN VOLUNTEER WHEAT. 



The occurrence of the larval fly in volunteer wheat in the lat- 

 ter part of summer or early in fall has been already reported 

 more than once by farmers, but has commonly either been dis- 

 credited, or reckoned an occasional phenomenon, due to excep- 

 tional conditions. To an inquiry addressed last spring to a num- 

 ber of observant farmers, and others of my acquaintance, I 

 received several answers to the effect that the occurrence of the 

 larval fly in volunteer wheat was a common event in Southern 

 Illinois. 



Mr. George H. Stookey, of Freeburg, writes: "In regard to 

 the fly in volunteer wheat, if the stubble is plowed early— say in 

 July — I think the flaxseeds occur late* in August. I have noticed 

 that when there is volunteer wheat, if it is plowed under or i)as- 

 tured off, the Hessian fly is not nearly so destructive to the fol- 

 lowing crop." 



*Tlifi nppfiarance of InmKOH May 3-1, 1SH7, from puparia pollertcd at Edgewood, is to be added 

 to the nl)i>vo. 'I'licHe ImagoH dcpositiMl egKS it once, aH stated on another page. 



