138 Flies [CH. 
prevented from living during the winter on such 
grasses as couch. 
An attack is often most noticeable near hedges and 
ditches or strips of grass. This is probably because the 
fly has been living there during the winter. Grasses 
in hedges, ditches, and headlands should be cut and 
burnt during the winter. 
The straw from an infected crop should be stacked 
as tightly as possible or used at once for litter; either 
of these measures will prevent a large number of flies 
from hatching. 
A number of the puparia will be carried off in the 
swollen heads when the crop is harvested ; on threshing 
they may be found in the cavings and should be 
destroyed. Winter corn sown near an infested field 
should be put in rather late, so that the second brood 
of flies may not be able to lay their eggs on this 
crop. 
When the attack is so bad that there is little hope 
for the crop it is better to sheep off the barley. 
The stubble should be turned under as deeply as 
possible with a skim coulter soon after the crop is 
harvested, by which means many of the puparia will 
be buried. 
Hessian Fly (Cecidomyia destructor). 
This fly occasionally damages wheat, barley and 
rye. It also lives on grasses, such as couch and 
timothy. 
Wheat suffers most from it and the effect is usually 
noticed when in full ear. Plants here and there are 
seen to have fallen down. This condition goes by the 
