Weevils in Beans and Peas. 81 
at 131° F.; full-grown larve in beans die in 20 minutes at 131° F.; 
and pup die in beans when exposed for 25 minutes at 131° F. 
Adults are killed by a 4-minute exposure to 131° F. These data can 
not be relied upon when large masses of seed are to be treated. The 
investigator who obtained them found that 9 hours were required for 
the center of 2 quarts of beans inclosed in a tight paper bag to reach 
the surrounding temperature of 131° F. Cowpeas infested with the 
four-spotted bean weevil were not absolutely sterilized from an 
insect standpoint when exposed to 140° F. for 5 minutes, though 
all the weevils were killed when the seeds were exposed to this 
temperature for 10 minutes in an oven. These results in killing the 
four-spotted bean weevil were secured under conditions more favor- 
able than those likely to occur in commercial bean establishments, 
hence it was recommended that seeds be exposed in commercial treat- 
ment to 146° F. for 20 to 30 minutes. Temperatures above 150° F. 
seemed to weaken the resulting plants, but germination took place 
even after the seeds had been subjected to 190° F. for 10 minutes. 
Commercial coffee roasters are used by certain bean brokers for the 
destruction of weevils by heat. Seeds have been treated by the car- 
load in such roasters and guaranteed to remain free from injury by 
bean weevils at least during transit in carload lots. A list of firms 
that manufacture apparatus for heating seeds will be furnished upon 
application. As is done in kiln-drying, the seeds should be spread 
out in order that all may be affected quickly and uniformly by the 
heat. When thus spread out an exposure to 131° F. for 1 hour should 
be sufficient. 
Heat is not recommended for the control of the broad-bean weevil 
in broad or Windsor beans. Exposure to temperatures ranging from 
120° to 140° F. for 5 to 40 minutes did not kill this apparently more 
hardy insect and the higher temperatures had an injurious effect 
upon germination. 
COLD AND COLD STORAGE. 
Weevils will not feed and cause damage at low temperatures. It 
is not known at what temperature development ceases, but no de- 
velopment takes place at or below 50° F. Cowpeas can be kept free 
from weevils if held in storage at a temperature of 32° to 34° F. 
It is claimed that exposure for a season at this temperature does not 
affect the germinating power of the seed. Investigations conducted 
in this bureau and not yet completed indicate that no stage of the 
common bean weevil can withstand 56 days of cold storage at 31 to 
32° F., although they may survive more than 66 days at 36° F. The 
larve, it appears, succumb to cold storage temperatures more readily 
