38 
abdomen is a little shorter, the whole insect being from .06 to .07 
of an inch. The legs have all the femurs yellow, front tibiae 
yellow, middle and hind tibiae fuscous, except at the apices, which 
are yellow; feet as in the females. 
(Cecidomyia destructor, Say.) 
I 
he 
3. Contributions to a Knowledge of the Life History and the 
Parasites of the Hessian Fly. 
Order Diptera. Family Cecidomyidje. 
uMw 
(Plates £1 and III.) ^ 
m I 
Notwithstanding the enormous losses inflicted upon agriculture in 
Illinois by this most destructive enemy of one of our important 
staple crops, the details of its life history, upon which strictly 
depend the value of measures for the prevention or control of the 
injuries, have not been fully or accurately made out for any part 
of the Mississippi Valley, the statements current on this subject 
appearing in agricultural papers and in the writings of our local 
entomologists, being mostly derived from the statements of HerHck, 
Fitch, Harris, and other observers, who have studied the species in F 
the North Eastern States. 
It is, beyond question, chiefly to its parasitic enemies that we 
owe such immunity from the Hessian fly as we now enjoy, these 
clearly constituting the principal natural check upon its continued 
existence in destructive abundance; but our ignorance of its para¬ 
sites is even greater than that of its life history, for almost noth¬ 
ing definite has been learned concerning them since the observa¬ 
tions of Herrick, of Connecticut, made in 183*2 ; Certainly, therefore, 
time and labor spent in acquiring more definite knowledge of the 
details of the life history of the Hessian fly, and the number, 
kinds, seasons and habits of the parasites will be well employed, 
even if it should serve only to shake the confidence of our agricul¬ 
tural community in such remedial measures as may have been 
heretofore recommended. 
As soon after entering upon the duties of State Entomologist as 
time and opportunity offered, I began observations upon this insect 
with the view and hope of constructing a complete account of its 
life history in the southern half of Illinois,—the only region late y 
affected by it, since winter wheat culture, although now rising to 
importance in the northern part of the State, has been too lateq 
revived there to expose the flelds to danger from the Hessian fly* 
The results here presented fall something short of a comple e 
account of the life history of this insect throughout the year, bu 
they nevertheless throw unexpected light upon the matter, and are 
deemed worthy of report as a statement of the present condition o 
the investigation. 
