89 
observations were directed almost wholly to the midsummer 
• of the insect, the facts respecting its autumnal injuries and 
ernation being sufficiently well settled. As a fair example of 
rrent view of the summer history, we may take the following 
t from Packard’s “Guide to the Study of Insects”: 
j) flies appear just as the wheat is coming up; they lay their 
)r a period of three weeks, and then entirely disappear. The 
ts hatched from these eggs take the flaxseed form in June 
fly, and are thus found in the harvest time, most of them 
ling on the stubble. Most of the flies appear in the autumn, 
aers remain in the puparium until the following spring. By 
g the stubble in the fall, their attacks may best be prevented.” 
.11 be seen, however, from the observations here reported, that 
ove history is inaccurate for Southern Illinois, and that the 
Y mentioned by the author is, as a consequence, to a great 
inapplicable.* 
dlowing the life history of the fly through the season by means 
iiding experiments and field observations and collections, the 
ial embarrassment has arisen from the immense prevalence 
asitism in the summer brood, so that breeding cages contain* 
rdes of the larvae and flaxseeds would yield scarcely a single 
d fields in which they had destroyed the crop would send forth 
of the adult insects that the most diligent sweeping at the 
of their emergence would not obtain a single specimen. 
. 
LIFE HISTORY. 
1888. 
observations for 1888 began at Centralia, April 10, at the 
Vhen the Hessian fly was abundant in the pupa state, and 
so rapidly emerging in the winged form. From a large num- 
wheat plants containing the flaxseeds sent to Normal at this 
flies continued to emerge until the 20th of the month, after 
no more appeared. These imagos laid their eggs in the 
{jig cages almost from the first. 
the 5th of May young larvae of the spring brood were collected 
^uoin, some of them scarcely more than hatched, and others 
own. These were placed in a closed fruit jar in a room ad- 
y the office at Normal, and kept under cover at the ordinary 
Aature of the out-door air; and to my surprise, on the 28th 
y, two imagos appeared in the jar. Upon June 4, four more 
3 d, three males and one female, and others at intervals until 
j['L5. 
The 17th of May, examples of both free larvae and flaxseeds 
eceived from Odin, in Marion county. On the 24th, we col- 
larvae only, from wheat fields in Decatur, in Macon county, 
, 3 but fair to state that in his later papers Dr. Packard revokes the recommenda- 
ted above, for the burning of stubble in fall, and describes it on the contrary as a 
> likely to be productive of the greatest harm; but not on the ground that the 
s, which it is intended to destroy, have most of them given exit to the fly, but 
n ground which seems to me wholly untenable, viz: that the harm done by the 
ion of the parasites must far overbalance the benefit done by burning the 
s in the field. 
