27 



From these puparia, October 18, three adults emerged — two males 

 and a female. These were confined, alive, in a small bottle, and 

 the single ferfiiale at once laid eggs freely on the sides of the 

 bottle, but nowhere else. B}' the next morning after the appear- 

 ance of these imagos, this single fly had perished after laying 

 sixty-seven eggs. 



On the 16th November, this plot of August wheat contained an 

 abundance of naked larv?e, with a few recent puparia. A handful 

 of wheat sent to the office contained one hundred and ninety-one 

 immature specimens,— fifty-eight being darkened puparia, thirty- 

 one pup-aria freshly formed, and one hundred and two larvae of 

 various sizes, from two millimeters up— the smallest seven aver- 

 aging about two and a half millimeters in len{2;th. Search in the 

 other wheat fields of this vicinity gave no evidence whatt^ver of 

 the occurrence of the fly. 



If we scan now more closely the results in these experimental 

 plots, we shall note in the first place a much later appearance of 

 the fly than the reports of my correspondents had given 

 reason to anticipate. While the letters quoted agree substantially 

 that full grown larvae and puparia appear in wheat from the last 

 of August to the middle of September, our own earliest examples 

 were obtained September 22 (Edgewood), at which time few or 

 none of the larvae were more than half grown; and the specimens 

 sent from Billett Station on the 28th September were in about 

 the same relative stage of advancement. 



The late appearance at Edgewood might be reasonably attrib- 

 uted to the failure of the earlier sowings to germinate, no wheat 

 being in condition to attract females in search of suitable places 

 for the deposition of their eggs until about August 15 or 20. As 

 the time for the maturing of the brood is seen, however, to vary 

 little from six weeks at that season of the year, it is likely that 

 at Edgewood the eggs were laid about September 21. On the 

 other hand, at Billett Station, where the rain-fall was much more 

 timely and abundant, there was no such failure of tlie earlier sow- 

 ings; and we can only adjust the facts there observed to the 

 theory of a normal earlier development of the midsummer flies by 

 supposing that the overwhelming attack made upon the first two 

 plots by the wheat bulb worm, prevented the female Hessian flies 

 from resorting to the s^me wheat. Evidently, however, another 

 season's experiments will be needed to explain these discrepancies. 



A further item of interest appears when we compare the con- 

 dition of the fields at Edgewood and Billett Station, October 12. 

 At the former j)lace, about ninety-five per cent, of the larvae had 

 formed the puparia, while at Billett Station no more than ten per 

 cent, were so far advanced, the remainder being naked larvae of 

 all sizes, from the smallest up. This discrepancy is, however, ex- 

 plained without difficulty by the different surroundings of the 

 fields. The one at Edgewood being the only tract in the entire 

 region in which we were able to find before harvest any traces of 

 the fly, it probably became infested only from the flies which de- 



