44 THE HESSIAN FLY IN THE UNITED STATES. 
early enough to attract the flies, and should in any case be plowed 
under as deeply as practicable. The proper time for sowing decoys will 
vary with the latitude. According to Webster, for northern Indiana 
they should be sown during the latter part of August, and in the 
southern part of the State not later than the first week in September. 
To the north and south of this he does not undertake to give dates, 
but it would depend upon the date of appearance of the fall brood of 
flies, the wheat being planted early enough to attract the flies at the 
time of their emergence. A decoy crop should be destroyed within 
four weeks at the utmost, and turned under so deeply that any insects 
maturing would be unable to escape. 
EARLY OR LATE SOWING OF FALL WHEAT. 
In winter- wheat regions the time of sowing in autumn is, with refer- 
ence to the Hessian fly, a very important item. Early-sown wheat will 
naturally be exposed to the deposition of eggs by flies issuing in the 
autumn, but, on the other hand, if the plants have got well started and 
thrown out numerous tillers there is much less danger of their complete 
destruction, and if the flies should not be numerous a considerable gain 
may result. The principal objection to this view would seem to be that 
the multiplication of the insect is encouraged and there would be a 
strong probability of more serious attack the following spring. Early 
sowing may be practiced if desired, especially on a small scale, and then 
if it is found that the crop is considerably infested it may be plowed 
under the same as a decoy crop and the field resown later. 
Late sowing of fall wheat has been one of the principal resources 
against the Hessian fly, and the writings of most of the leading ento- 
mologists have agreed in a strong recommendation of this policy. 
Packard quotes numerous writers in support of this general plan, and 
it appears to be very generally adopted by farmers. To be successful 
the sowing should be late enough so that the plants do not appear above 
ground until after the bulk of the Hessian flies have issued and died. 
It has been shown, however, that the flies may emerge quite late in 
the season and deposit eggs even after frosts are common. Marchal 
remarks that in Vendee the wheat sown after October 20 has been 
completely free from injury. In the practical use of this remedy it 
becomes essential for the farmers of any given latitude to determine 
the time of appearance for the bulk of the autumn brood of flies and 
to time the late sowing accordingly. This will be a progressive date 
from north to south. Webster says: 
If farmers in the extreme northern part of Indiana and in southern Michigan can 
sow their wheat with safety about the 12th to 15th of September (and we have dem- 
onstrated that the fall brood emerges largely prior to the 15th), and farmers in the 
extreme southern part of Indiana delay sowing until after the first days of October, 
there must be a general system of retardation which, if understood, may be used to 
advantage throughout the intervening territory. 
Starting in southern Michigan on the 12th or 15th of September and passing 4 
