The Chinch Bug and Its Control. 13 
such quarters. Likewise, the insect can withstand the most severely 
hot summers, provided it is not long exposed to the direct rays of the 
sun. In Kansas and Oklahoma large numbers of the bugs are oc- 
casionally killed by being knocked from the plants by harvesting 
when the soil temperature is as high as from 125° to 135° F. In such 
cases the bugs perish before they are able to travel the 6 to 12 inches 
to shelter. Most of the bugs escape exposure to such conditions by 
remaining behind leaf sheaths of corn, kafir, and other crops, or by 
staying among the roots in soil shaded by the plants, moving from 
one plant to another only in the late afternoon or early forenoon. 
The amount of moisture in the air apparently has no appreciable 
effect in reducing the abundance of the pest, and it can withstand not 
only the humidity of the tropics but the continuous drenching rains 
- of more northern latitudes. While it is true that the years of 
greatest devastation by the chinch bug have largely followed a suc- 
cession of years of deficient rainfall, the amount of annual rainfall can 
not be depended upon in predicting outbreaks. Chinch bugs have 
sometimes been exceedingly numerous and destructive in years of more 
than normal rainfall. Even if the precipitation occurring only 
during the active season of the bugs (April to October) is considered, 
it may fail to give us a basis of prediction. Much depends upon the 
character of the rainfall. 
DISEASES. 
The abundance and consequent worth of fungous diseases known 
to attack the chinch bug are entirely dependent upon the occurrence 
of wet, cloudy, and cool weather during most of the hatching and 
growth period of the young bugs. This dependence upon a par- 
ticular kind of weather ordinarily prevents these diseases from 
destroying the bugs in large numbers. 
The principal disease, known as the chinch-bug fungus,?? has 
been purposely introduced among the bugs in Kansas, Nebraska, and 
Illinois, without practical commercial benefit in preventing damage. 
Its efficiency depends very largely upon exceptional seasonal pre- 
cipitation, just the conditions which of themselves alone are most 
unfavorable to the chinch bug. In seasons when the bug can thrive 
best. least can be expected of the fungus. The disease attacks many 
other insects, and is present every year throughout most of the 
chinch-bug territory. Therefore, it would become exceptionally 
abundant in unusually favorable weather without artificial intro- 
duction, whereas cultures introduced in unfavorable weather would 
be held to the normal level of the disease. The control of the chinch 
bug by introducing fungous disease has so far failed. Where the 
22 Beauveria globulifera (Speg.) Picard. 
