Apr. 26, 1924 
Fumigation of Bean Weevils 
349 
Table I.— The effect of fumigation on adult weevils , Bruchus obtectus 
Number of 
weevils 
Date. 
fumi¬ 
gated 
Material used 
Dos¬ 
age 
per 
1,000 
cubic 
feet 
Expo¬ 
sure 
Num¬ 
ber 
alive 
Num¬ 
ber 
dead 
Temperature 
Humidity 
Maxi¬ 
mum 
Mini¬ 
mum 
Maxi¬ 
mum 
Mini¬ 
mum 
• 
Lbs. 
Hrs. 
°F 
°F. 
100___. 
Apr. 19 
CS 2 _ 
2 
24 
0 
100 
61 
53 
70 
66 
100.. 
...‘do. 
-do... 
2 
24 
0 
100 
61 
53 
70 
66 
60__ 
...do_ 
_do_ _ _ 
2 
24 
0 
50 
61 
53 
70 
66 
100.. 
(°) 
100 
0 
76 
49 
68 
41 
100_ 
Apr. 20 
CS2. 
3 
24 
o 
100 
58 
53 
70 
66 
100. 
...do_ 
_do __ 
3 
24 
0 
100 
58 
53 
70 
66 
60_ 
...do. 
_do__ 
3 
24 
0 
50 
58 
53 
70 
66 
100. 
(«) 
100 
o 
75 
49 
75 
45 
100. 
Apr. 21 
CS 2 __ 
1.5 
48 
o 
100 
68 
60 
64 
59 
100_ 
*(°) 
100 
6 
85 
50 
70 
29 
100. 
Apr. 23 
CS2. 
1. 5 
48 
o 
100 
60 
52 
68 
59 
100_ 
( a ) 
100 
o 
69 
41 
68 
19 
100. 
May 13 
____ 
cs 2 ... 
... 
3 
21 
o 
100 
68 
62 
73 
71 
100.... 
( a ) 
100 
o 
81 
60 
82 
53 
60__ 
May 17 
&Liq. HCN.. 
1.8 
24 
o 
50 
70 
62 
70 
45 
50. 
_do_ 
_do__ _ 
1. 8 
24 
o 
50 
70 
62 
70 
45 
60.. 
( a ) 
50 
0 
85 
51 
92 
44 
50. 
June 8 
CS2. 
6 
21 
o 
50 
68 
64 
70 
66 
50.. 
( a ) 
50 
0 
87 
50 
83 
50 
50_ 
June 11 
Liq. HCN. 
3. 5 
48 
0 
50 
75 
62 
80 
58 
50. 
...do_ 
.do__ 
3.5 
48 
0 
50 
75 
62 
80 
58 
50__ 
...do. 
_do.. 
3.5 
48 
0 
50 
75 
62 
80 
58 
50... 
(«) 
50 
0 
83 
64 
82 
64 
50. 
(«) 
50 
0 
83 
64 
82 
54 
50.. 
( a ) 
50 
0 
83 
64 
82 
54 
° Control. 
h All fumigation by the use of liquified hydrocyanic acid was done in cooperation with E. R. Hulbirt 
of the Owl Fumigation Corporation of Azusa, Calif. 
Table II shows that all emerged adult four-spotted cowpea weevils, Bruchus 
quadrimaculatus , were killed by an exposure of 24 hours to 1.8 pounds of liquefied 
hydrocyanic acid at 62° to 70° F., and that 1.3 pounds was equally effective 
when the exposure was extended to 90 hours at a temperature ranging from 58° 
to 91° F. In a 29-inch vacuum where carbon disulphide was used at the rate* * of 
31 pounds per 1,000 cubic feet at a temperature of 82° F. all emerged adults were 
killed in one hour. 
Table II.— The effect of fumigation on adult weevils , Bruchus quadrimaculatus 
Number of 
weevils 
♦ 
Date. 
fumi¬ 
gated 
Material used 
Dos¬ 
age 
per 
1,000 
cubic 
feet 
Expo¬ 
sure 
Num¬ 
ber 
alive 
Num¬ 
ber 
dead 
Temperature 
Humidity 
Maxi¬ 
mum 
Mini¬ 
mum 
Maxi¬ 
mum 
Mini¬ 
mum 
Lbs. 
Hrs. 
°F. 
°F. 
50. 
May 17 
Liq. HCN. 
1.8 
24 
0 
60 
70 
62 
70 
45 
50. 
(«) 
50 
0 
85 
51 
92 
44 
50__ 
Aug. 16 
Liq. HCN. 
2 
48 
0 
50 
92 
64 
79 
46 
50. 
...do_ 
.do___ 
2 
48 
0 
50 
92 
64 
79 
46 
50. 
(°) 
48 
2 
92 
64 
79 
46 
50__ 
(a) 
47 
3 
92 
64 
79 
46 
50 
Aug. 17 
CS 2 and 29-inch 
31 
1 
0 
50 
82 
82 
vacuum . h 
50.. 
...do_ 
_do__ 
31 
1 
0 
50 
82 
82 
50.. 
(°) 
50 
0 
92 
64 
79 
46 
50 . 
(a) 
50 
0 
92 
64 
79 
46 
50. 
Aug. 18 
Liq. HCN_ 
1.3 
90 
0 
50 
91 
58 
79 
43 
60. 
_do_ 
_do. 
1.3 
90 
0 
50 
91 
58 
79 
43 
60. 
( a ) 
45 
5 
91 
58 
79 
43 
60.. 
(°) 
46 
4 
91 
58 
79 
43 
60.. 
Aug. 23 
HCN, pot method «. 
*3.4 
48 
0 
50 
82 
69 
71 
51 
60_ 
...do_ 
.do.. 
* 3. 4 
48 
0 
50 
82 
69 
71 
51 
60. 
...do_ 
_do__ 
*3.4 
48 
0 
50 
82 
69 
71 
51 
60. 
(«) 
60 
0 
82 
69 
71 
51 
50.. 
Aug. 25 
HCN, pot method e . 
1.8 
90 
0 
e 50 
84 
67 
66 
51 
50. 
C) 
* 50 
0 
84 
67 
66 
51 
a Control. 
b In the experiments with vacuum fumigation the material was prepared by the writer and fumigated 
by Mr. D. B. Mackie, of the California State Department of Agriculture, after which tabulations were 
made by the writer. 
e For economy of space in the tables, “HCN, pot method” is used to designate hydrocyanic-acid gas 
generated by the pot method. 
* Dosage of sodium cyanide employed to generate the gas. 
• These weevils emerged on Aug. 24. 
