32 
THE CHINCH BUG. 
years of greatest abundance of the chinch bug were preceded by a 
series of years during which there had been a deficiency in the rainfall 
over the area of country devastated by this species. In fact, it has in 
a general way come to be understood that dry seasons are favorable 
and wet seasons unfavorable for the development of the chinch bug, 
though the details of the phenomenon have never been very carefully 
Fig. 7. — Ma|> showing distribution of chinch bug in Ohio in 1896 (from Bull. No. 6, n. s.). 
and elaborately worked out. The entomological and meteorological 
records of the past have, however, clearly shown that the amount of 
the annual rainfall is not a safe guide in this problem. Chinch bugs 
have occurred in excessive numbers during years of heavy precipitation. 
The term u wet season," so frequently used in this connection, is an 
indefinite one, but if the term "season" be restricted to the period of 
time intervening between the verual and autumnal equinoxes we shall 
