RE eas 
Weevils in Beans and Peas. 93 
HEATING DUE TO INFESTATION. 
It is a well-known fact that beans and peas, as well as grains, 
will heat if insects become sufficiently abundant in them. In bean ware- 
houses where the seeds are stacked as shown in Figures 26 and 27, 
centers of weevil infestation can be detected by walking past the 
tiers of sacks and allowing the hand to pass over the sacks. Experi- 
ence soon makes it easy to detect heating sacks. Heating seeds also 
produce an odor quickly detected by experienced persons when they 
enter a warehouse after it has been closed for a few hours. 
The ability of bean and pea weevils to produce heating of the seeds 
is of great importance. Were it not for this ability, owners could 
Tic, 25.—Navy beans cut crosswise to prove how the common bean weevil can ruin 
seeds for eating or planting. About natural size. 
rest assured that if warehouses were open to outdoor temperatures 
below 50° F. no injury from weevils would take place. Certain wee- 
vils develop most quickly when the temperature ranges between 75° 
and 95° F. and egg laying is greatly stimulated by these higher tem- 
peratures. At temperatures ranging from 75° to 95° F. development 
of the four-spotted bean weevil has been known to be completed in 
as few days as 18; hence heating caused by weevil infestation, with 
the accompanying increase in moisture content of the seeds, may 
result in an outbreak of weevils at a season of the year when least 
expected. The temperature of a 240-pound sack of chick-peas in- 
fested by the cowpea weevil and the four-spotted bean weevil may be 
raised by infestation to at least 103° F. It is not uncommon in some 
warehouses to find a considerable number of sacks the temperature 
of which has been raised to over 80° or 90° F. In one instance, when 
the daily maximum temperatures ranged between 50° and 58° F., 
sacks within 2 feet of an open window registered 102° F. The tem- 
perature in the spaces between heating sacks was raised in this ware- 
