14 THE HESSIAN FLY IN THE UNITED STATES. 
the localities farther north. In general, for the territory lying north of 
42 J° north latitude west of the Mississippi River, the insect is practi- 
cally unknown to the majority of the iarniers and no account is taken 
of it in their calculations on the wheat crop. 
The conclusion seems warranted that while the Hessian fly may sur- 
vive in this region in small numbers, and occasionally so multiply as to 
attract attention in limited localities, that the conditions for its increase 
are too unfavorable for it to multiply greatly. These conditions would 
seem to be the general occurrence of a considerable period of dry weather 
in midsummer and autumn, and absence of food plants, thus forcing 
the insect to become single brooded. This greatly reduces its power of 
multiplication, exposes it to destruction by desiccation, or starvation, 
and the greater activity of parasites. If the insect ever becomes 
troublesome in this region it would seem a most simple matter to con- 
trol it by simple adaptation of proper measures, especially the resort 
to burning the stubble and early plowing under, discussed in detail in 
the chapter on remedies. 
From all that could be learned, and from the previous history of the 
insect in this region, it seems to me fair to conclude that the Hessian 
fly is not a menace to the wheat industry of this region, as was feared 
when its extension into this territory was first noted. The natural 
conditions prevailing in the region, with the ready multiplication of 
parasites, will serve to keep it in check during ordinary years. If 
farmers will only recognize the characteristic breaking down of wheat 
due to its presence, and in years when this is noted proceed to burn 
the stubble or plow it under and roll, they can prevent its multiplica 
tion and the possible damage that might follow in the succeeding 
year. 
DESCRIPTION AND LIFE HISTORY. 
The descriptions of the Hessian fly have been quite numerous, and 
some of them given with considerable accuracy of detail, so that there 
should be little difficulty in distinguishing the species from related 
forms. In many cases it is, however, deficient in characters which defi- 
nitely separate it from the most closely related forms. It is clearly of 
no little importance to have a positive basis for the separation of the 
insect from related forms, particularly those which occur in closely 
related plants, and especially if they agree with it in the character of 
the puparia. 
The adult insect (Plates I and II), like other members of the family 
Cecidoinyidse, to which it belongs, is a small, guat-like, two-winged 
creature, about half as large as a common mosquito, which it resembles 
in form. 
The female is about one-tenth of an inch long (2.5 mm.), of a dark 
color, the abdomen in freshly issued specimens appearing red, with, 
black patches or bands of black, and with red bands at the articula- 
tions, depending upon the amount of distension. 
