21 
SECOND CONTRIBUTION TO A KNOWLEDGE OF THE 
LIFE HISTORY OF THE HESSIAN FLY 
(Cecidomyict destructor , Say)A 
In the valuable monograph on the Hessian fly published in the 
Report of the United States Entomological Commission (1883), 
e following summary of the facts relating to the life history of 
e species is given: 
“There are two broods of the fly, the first laying their eggs on 
e leaves of the young wheat from early April to the end of 
ay, the time varying with the latitude and weather; the second 
ood appearing during August and the early part of September, 
d laying about thirty eggs on the leaves of the young winter 
a eat. 
“The eggs hatch in about four days after they are laid. Several 
the maggots or larvae make their way down to the sheathing 
tse of the leaf, and remain between the base of the leaves and 
e stem near the roots, causing the stock to swell and the plant 
turn yellow and die. By the end of November, or from thirty 
forty days after the wheat is sown, they assume the ‘flaxseed’ 
[ate, and may, on removing the lower leaves, be found as little 
rown, oval, cylindrical, smooth bodies; a little smaller than grains 
i rice. They remain in the wheat until during warm weather; 
April the larva rapidly transforms into the pupa within its 
ixseed skin, the fly emerging from the flaxseed case about the 
Ld of April The eggs laid by this first or spring brood of flies 
on hatch; the second brood of maggots lives but a few weeks, 
e flaxseed state is soon undergone, and the autumn or second 
■ood of flies appear in August. (In some cases there may be 
?o autumn broods, the earliest August brood giving rise to a 
ird set of flies in September).” 
It was especially to test, for the latitude of Southern Illinois, 
e details of this, the current biography of the Hessian fly in 
inerica, that I commenced observations on the subject in South- 
n Illinois in 1883. The results thus far established show that 
that latitude a large percentage, at least, of the flies emerge 
imagos before wheat harvest or immediately thereafter (May 
> to June 28); that, if opportunity offers, the fly will breed 
*For a previous contribution, which includes an account of the parasites, see 14th Rep. St. 
t. Ill., pp. 38-50. 
