18 
rules and preventives failed absolutely and the loss of the wheat crop 
yas almost total. 
Unfortunately, similar conditions threatened the growing crop 
(1900-1901). The enormous abundance of the flies and a late and very 
mild autumn have resulted again in an extraordinary infestation by 
this insect over large areas. 
The breeding of the Hessian fly during the autumn of 1900 con- 
tinued in some localities very late. Mr. E. P. McCaslin, Seymour, 
Ind., who has been making very careful study and frequent reports on 
this insect for this office, supplies data showing that the wheat sown 
in that locality between October 9 and 15 was badly infested by the fly. 
The insect began hatching as early as the 1st of September and contin- 




2 P Ria DS pelt Lube 





Fie. 8.—Map showing distribution of Hessian fly in America (reduced from Webster). 
ued in evidence until the Ist of October, a supplemental brood appear- 
ing after October 22. The winter was so mild that undeveloped larve 
were abundant in wheat into the second week of December. A short 
period of zero weather in the middle of December did not destroy the 
laryee (fig. 9), but a prolonged cold spell beginning about Decem- 
ber 22 killed most of the larve that had not passed into the flaxseed 
stage. That the insect will hatch from the flaxseed stage without long 
hibernation if kept in a warm place was illustrated by material coming 
into this office which yielded flies in great numbers during January 
and February and deposited eggs from which young larvee emerged. 
The effect of drought on the Hessian fly was very interestingly 
shown by the season of 1899-1900. As pointed out by Professor Web- 
ster, a severe dry spell sufficient to prevent the germination of wheat, 
132 
