INFLUENCE OF TEMPERATURE ON CHINCH BUG. 37 
have more definite grounds upon which to base our studies of meteoro- 
logical influences. Thus applied, the terms “ wet” and “ dry ” sea- 
sons would include within them the two breeding periods of the 
chinch bug, at least largely so, north of latitude 30° N. But the his- 
tory of this species has shown that there may be an excess of rainfall 
during this critical period and that still a sufficient number of insects 
may develop to work serious injury over considerable areas of coun- 
aim! 
Vl 
GUERNSEY 
= 
6 
, 
, 
y 
m 
: \ 
H1g. 11.—Map showing distribution of chinch bug in Ohio in 1896. (Author’s illustration. ) 
try. This is due to two, and perhaps more, causes. In the first 
place, an unusually heavy rainfall at long intervals, while bringing 
up the total for a given period, may have but little effect in reducing 
the number of chinch bugs, while a much less amount of precipitation 
coming at short intervals and in the midst of the hatching season 
would cause a far greater mortality among the young. And, in the 
second place, the precipitation may come at the beginning or even 
