THE HESSIAN FLY. 17 
infestation is apparent (see fig. 10), will cause the plants to tiller 
more freely and give them sufficient vigor to withstand the winter, 
and thus increase the number of healthy stems the following spring. 
Any other means that could be employed having a similar effect 
would be a remedial measure. 
All practical measures must necessarily be in the nature of pre- 
ventives, looking (1) to the elimination of the pest in the young 
wheat in the fall, and (2) to the increasing of the vigor of the young 
plants in order to enable them to counteract the insect’s effect, when 
present. Under the first come late sowing, rotation of crops, burn- 
ing of the old stubble, and the destruction of volunteer wheat. 
Under the second should be classed the enrichment of the soil, its 
thorough preparation, and selecting and properly sowing the best 
seed. 
By late sowing as here recommended is meant moderately late 
sowing of fall wheat in any locality, for extremely late sowing, which 
has sometimes been advised, would be even worse than early sowing. 
The later appearance of the fly in the fall, as we pass from the north 
Fia. 14.—Hupelmus ailynii, a parasite of the Hessian fiy: Female. Much enlarged. (Original.) 
LATE SOWING. 
southward, has already been explained. At present the Bureau of 
Entomology is conducting experiments in fall wheat sowing in nine 
States, covering approximately the country between latitude 33° 
and 46°. Here wheat is being sown every ten days during Septem- 
ber, October, and November, year after year, with the expectation 
of determining the approximate date of safety for seeding in the fall 
to evade attack of the fly. While these experiments have not been 
going on for a long enough time to give results sufficiently definite, 
covering all variations in the weather during these months, it is 
safe to say that wheat may probably be sown, without danger from 
Hessian fly attack, in northern Michigan soon after the first of 
September; in southern Michigan and northern Ohio, about Sep- 
tember 20; in southern Ohio, after the first week in October; in 
Kentucky and Tennessee, October 10 to 20; in Georgia and South 
Carolina, October 25 to November 15. In extreme southern Kansas 
and northern Oklahoma wheat should not be sown until after the 
first week in October; and this is true of Virginia. October-sown 
