12 Farmers’ Bulletin 1223. 
gradually die off during October and November; the remaining 
adults then finally seek permanent hibernating quarters for the 
winter. 
CONDITIONS FAVORING OUTBREAKS. 
If growers will take the trouble to watch certain field and weather 
conditions they usually will be able to tell when an outbreak of 
chinch bugs threatens. The most important among the conditions 
favoring outbreaks are: (1) Suitable hibernating places, and (2) 
warm, fairly dry weather during the two critical hatching periods, 
May to June and August to September. 
In the northern and middle range of the insect, it must have hiber- 
nating places capable of harboring large numbers of adults in a 
position well sheltered from natural enemies and disease. Its win- 
ter shelter must be dry and must contain sufficient green plant food 
to tide it over the periods of warm weather that may occur after it 
has begun hibernating and before the advent of cold weather, and in 
the spring before conditions are right for migration to its regular 
food plants. In its southern range its hibernating quarters must 
supply food for these periods and must be of a sort that will protect 
it from a succession of warm, thawing days followed by freezing. 
Even if these conditions are met and a fairly good percentage of 
the bugs get safely through the winter, transfer to the grain crops, 
and have favorable, warm, dry weather for depositing their eggs, a 
severe outbreak may still be prevented by a series of drenching rains 
and prolonged wet, humid weather during the hatching periods. 
These periods are, for the first generation, throughout May, overlap- 
ping into June and extending slightly into July, and for the second 
generation August, overlapping into September, and in the south 
extending into October. 
NATURAL CONTROL. 
NATURAL CONTROLS NOT DEPENDABLE. 
That the chinch bug can withstand almost every conceivable cli- 
matic variation is shown by the fact of its distribution from little 
north of the equator to nearly 50° north latitude, and from more 
than 200 feet below sea level, in the Imperial Valley of California, 
to upwards of 6,000 feet above sea level in the mountain regions. So 
far as the influence of cold is concerned, it is only in the least pro- 
tected situations that severe winter weather has much effect in reduc- 
ing the abundance of the pest. Chinch bugs have been known to 
withstand temperatures of from 15° to 20° F. below zero,even when 
incrusted with a coat of ice. Undoubtedly they must have hibernating 
quarters that will afford protection, and they are usually able to find 
