6 
matic conditions, and also to the abundance from time to time of the 
parasitic and other enemies, which is a natural sequence of the multi- 
plication of the host insects. This results in a more or less striking 
periodicity in the recurrence of the common grain pests. Fortunately 
in many instances these periods of unusual abundance are separated by 
wide intervals of comparative freedom. Sometimes, also, a season 
which is unfavorable for one insect is favorable for another. Hence 
we have not only a periodicity in the recurrence of the same insect, 
but a more or less marked rotation of the different species. All of 
this emphasizes the need on the part of the wheat grower of a thor- 
ough acquaintance with these different insect enemies, and with the 
climatic and other conditions which are liable to promote their abun- 
dance, and especially with the measures which may be taken to pre- 
vent or limit loss. 
The annual losses resulting from the attacks of these several insects 
on wheat is undoubtedly very great, running far into the millions in 
bad years, no very censiderable percentage of which is made good by 
the enhanced value of the remainder of the crop. Much of this loss 
can undoubtedly be prevented by proper attention to cultural methods 
and the adoption of known remedies. 
In the accounts of the chief wheat pests which follow, an effort has 
been made to give a brief presentation of the life histories of the sev- 
eral species treated, with special reference to the bearing of remedial 
and preventive measures. 
THE CHINCH BUG. 
( Blissus leucopterus Say.) 
The chinch bug (fig. 1) is certainly responsible for as great annual 
losses to farm crops as any other injurious species of insect known, 
and it is very improbable that any other species causes anything like 
the damage which is chargeable to this pest. This is due to its wide 
distribution, its prevalence more or less every year, the enormous 
multiplication in favorable seasons, and to the fact that it attacks all 
the cereals and most forage plants. The losses caused by it vary 
greatly in different years, but are always experienced more or less in 
some locality or other. These losses may often amount toa very large 
percentage of the wheat and other cereal crops, and also later of the 
corn crop, and throughout the season of various forage crops. The 
losses for single States in one season have been estimated at from ten 
millions to twenty millions of dollars, and for single years throughout 
its range at above a hundred million dollars. Large as these figures 
are, when the actual estimates of shrinkage of yield of wheat and 
other grains, not to mention forage crops, are made, it will be seen 
that they are reasonable and probably within the true amount. Much 
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