102 
Journal of Agricultural Research 
Vol. XXVII, No. ? 
1,400 beans dissected contained 792 weevils, and the larvae showed a 
slightly greater percentage of mortality than pupae and a considerably 
greater percentage of mortality than unemerged adults. Judging from 
the conditions found in the dissected beans, 66 days at 36° F. killed all 
weevils. 
Table II .—Effect of a constant temperature of 36° F. on Bruchus obtectus 
Larvae. 
Pupae. 
Unemerged adults. 
Number of 
i 
Mortality, 
days in 
Num¬ 
Num¬ 
Num¬ 
Num¬ 
[Num¬ 
Num¬ 
all forms. 
storage. 
ber 
ber 
Mortality. 
ber 
ber 
Mortality. 
ber 
ber 
Mortality. 
alive. 
dead. 
alive. 
dead. 
alive. 
dead. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
14 
4 
22 
84. 61 
II 
21 
65. 62 
7 
17 
7 °- 83 
73 - 17 
22 
25 
28 
5 2 - 83 
4 
18 
81. 82 
7 
12 
63 - 58 
61. 70 
31 
11 
17 
60. 71 
3 
27 
90. OO 
9 
19 
67. 86 
73 - 25 
37 
6 
21 
77. 78 
8 
13 
61. 90 
10 
13 
56- 52 
66. 20 
46 
7 
24 
77. 42 
2 
18 
90. OO 
7 
17 
70. 8.3 
78.67 
61 
0 
20 
IOO. OO 
1 
25 
96. 15 
5 
23 
82. 14 
91. s? 
66 
0 
1 
220 
IOO. OO 
,o 
58 
IOO. 00 
0 
32 
IOO. 00 
100. 00 
Total... 
53 
! 352 
29 
180 
45 
133 
COLD STORAGE EXPERIMENTS WITH BRUCHUS QUADRIMACULATUS 
SCOPE AND METHOD 
The resistance to cold of the eggs of the four-spotted bean weevil was 
tested by refrigerating 40,000 eggs (estimated) on about 6,000 black-eye 
cowpeas, with controls estimated at 13,300 eggs on 2,000 black-eye cow- 
peas. The eggs were deposited during a period of a few days before the 
seeds were placed in refrigeration, and had not begun to hatch at that 
time. The cowpeas on which the eggs had been deposited were placed 
in four thin cotton sample bags, each containing about 4,000 seeds. 
The effect of cold upon the other stages of this insect was investigated 
by the cold storage of 12,000 black-eye cowpeas containing an estimated 
total of 36,000 weevils, with a control of 4,000 seeds infested to the same 
degree. Four sample bags were filled with the weevily cowpeas, each bag 
containing about 4,000. 
One bag of cowpeas bearing eggs and one containing weevily cowpeas were 
left in the laboratory as controls, and similar pairs of bags were placed 
in each of the temperatures tested: 20°, 32°, and 39 0 F. The refrigerated 
rooms were in a modem cold-storage plant at Pasadena, Calif., where the 
temperatures were not permitted to vary more than 1 0 F. either way. 
The weevily cowpeas used in the trials were taken from a ioo-pound 
bag which was “heating” because of heavy infestation; the temperature 
* within the bag varied from 95 0 to ioo° F. (14 to 35 0 F. above room 
temperatures when the readings were made). About 30 minutes elapsed 
between the time the samples were taken from the laboratory and their 
storage in the cold rooms. 
The cowpeas were examined at intervals, at which times samples of 
50 or of 100 seeds were taken from each bag and transferred to the 
laboratory, where they were kept at temperatures favorable to growth 
and reproduction. 
