13 
ations for experimentation with this disease have been made by various 
States, notably Illinois, Kansas, and Wisconsin, and the value of this 
method of control has been thoroughly tested by trained experts. The 
upshot of all this work has been to show that this agency of control 
is not of very great value. In other words, as already pointed out, 
unusual chinch-bug increase and damage are characteristic only of sea- 
sons of drought, and, unfortunately for the use of the diseases men- 
tioned, they are propagated successfully and are effective only under 
conditions of considerable dampness or following a wet period. The 
very conditions, therefore, which make the disease useful are inimical 
to the chinch bug and, as a rule, exterminate it without the artificial 
introduction of the disease germs. In fact, it seems to be pretty well 
established that the disease occurs very generally, doubtless attacking 
other insects besides the chinch bug's, and whenever the weather condi- 
tions are favorable it develops itself and accomplishes the destruction 
of the chinch bug without the necessity of artificial introductions. It 
is doubtless true that occasionally when the disease is introduced just 
at the beginning of a rainy spell it may take hold of the bugs a little 
more quickly and effect their extermination more promptly than would 
have been the case had no artificial infections been made. In the main, 
however, it is scarcely worth while to bother with or rely on the intro- 
duction of this disease. If suitable climatic conditions intervene, the 
disease probably will itself develop and the chinch bugs will disappear. 
If, on the other hand, droughty conditions prevail, the introduction of 
the disease will be of no service. 
The immature bugs seem to be especially susceptible to the action of 
this disease, the mature insects being much more rarely affected by it. 
Summing up the subject of preventives and remedies, it may be 
said that the ones of real value are the clearing of farms and adjacent 
lands of rubbish and deadened grass by burning, the adoption of a 
rotation of crops which will separate the small grains from the later- 
ripening crops such as corn and late-sown millet, and the adoption of 
the steps indicated to stop the migrating midsummer hordes. 
THE HESSIAN FLY. 
( Cecidomyia destructor Say.) 
Economic importance and general characteristics.—The Hessian fly 
(fig. 5) is one of the principal enemies of the wheat crop, the minimum 
annual damage due to it being estimated at about 10 per cent of the 
product in the chief wheat-growing sections of this country, which 
indicates an annual loss of 40,000,000 bushels and over. An injury of 
from 50 per cent to a total failure of the crop is not infrequent in cer- 
tain localities, and the resulting loss is proportionately greater. 
The parent insect is a very fragile, dark-colored gnat or midge, 
about £ inch long and resembling somewhat closely a small mosquito. 
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