36 LEAFHOPPERS AFFECTING CEREALS, ETC. 
MOWING. 
The possible control of the species by the cutting of the grass 
depends upon an adjustment of the mowing to about the time when 
the insect is present in the egg stage or at such an immature larval 
condition that it is unable to migrate from the fields: at such times 
close mowing of the grass will remove such eggs as may be included 
in the leaves or stems and by exposing the young larvae to a shortage 
of food as well as to the direct action of the sun, serve very materially 
in their reduction. A somewhat similar effect may be produced by 
providing for the very close pasturage of the grasslands during a 
certain period, if possible to correspond with that of the egg deposi- 
tion of the more common species, alternating with a period of absence 
of stock from the field so that the grass may have a period of rapid 
growth. 
BURNING. 
Undoubtedly one of the most effective means of destroying the eggs 
of the leafhoppers in autumn or early spring is the burning of the dead 
grass wherever this means is practicable, and it may be resorted to 
with the assurance that much will be accomplished. The difficulty 
in this treatment arises from the fact that some grasses will not with- 
stand burning except when the ground is frozen or wet enough so 
that the heat will not penetrate the surface and that, in cases where 
fields are freshly seeded to grass, the young plants may be injured 
by this treatment. This process is, perhaps, most available in the 
prairie regions, where the accumulation of dry material at the sur- 
face of the ground furnishes abundant opportunities for the applica- 
tion of fire for the destruction of eggs and hibernating forms, occur- 
ring in the locality. It is also especially applici.ble to the alternating 
strips of grass, in the localities where wheat and grass are planted 
side by side. Direct observations on this plan have shown some good 
results, but it has not had general use under conditions giving accu- 
rate results. In the prairie regions, before general settlement, the 
prairie fires were of very common occurrence, and while we can not 
determine just how much they have accomplished in the control of 
these insects, it is worthy of note that pasturage on these plains was 
of a very excellent quality and of long duration. One of the most 
positive evidences of the effectiveness of burning came under my 
observation in the spring of 1910 in Ottawa County, Kans. On a 
level tract of grassland adjacent to a stream, part of the surface had 
been burnt over a short time previously and the burnt tract was 
practically free from leafhoppers while the adjacent unburnt area, 
under otherwise identical conditions, was abundantly infested with 
hoppers of several different species. Even where the areas examined 
were closely adjacent or the burnt patches were surrounded by 
unburnt grass the difference was very noticeable. This was evi- 
