352 
Joumal of Agricultural Research voi. xxviii, No. 4 
Table V. —Percentage of weevils, Bruchus obtectus, that were dead within the beans 
after being fumigated with different amounts of carbon disulphide or hydrocyanic- 
acid gas for varying lengths of time a 
Amount fumigated 
Material 
used 
Dosage per 1,000 cubic 
feet 
Exposure 
Un¬ 
emerged 
adults 
Pupae 
Larvae 
Tem¬ 
pera¬ 
ture 
Hu¬ 
midity 
Full- 
grown 
Half- 
grown 
Young 
Maximum 
Minimum 
Maximum 
Minimum 
Alive 
Dead 
Alive 
Dead 
<D 
> 
i—» 
< 
Dead 
Alive 
Dead 
Alive i 
Dead 
Centals. 
Lbs. 
Hrs. 
°F. 
°F 
13__. 
CS 2 . 
2 
24 
* 58 
42 
54 
46 
6 
94 
6 
94 
0 
100 
61 
53 
70 
66 
Control_ 
84 
16 
81 
19 
60 
40 
50 
50 
0 
0 
76 
49 
68 
41 
13_ 
CS 2 .. 
2 
24 
37 
63 
38 
62 
25 
75 
0 
0 
0 
0 
61 
53 
70 
63 
Control. 
82 
18 
98 
2 
67 
33 
0 
0 
0 
0 
76 
49 
68 
41 
9_. 
CS 2 __ 
3 
24 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
58 
53 
69 
66 
Control.. 
75 
25 
94 
6 
53 
47 
0 
0 
0 
0 
75 
49 
75 
45 
9__. 
CS 2 -—. 
3 
24 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
58 
53 
69 
66 
Control_ 
64 
36 
88 
12 
100 
0 
0 
0 
0 
0 
75 
49 
75 
45 
9. 
CS 2 . 
1 5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
68 
60 
64 
59 
9_ 
_do. 
1.5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
68 
60 
64 
59 
Control_ 
70 
30 
61 
39 
79 
21 
0 
0 
0 
0 
85 
50 
70 
29 
9. 
CS 2 --.. 
1 5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
60 
52 
68 
59 
Control.. 
85 
15 
90 
10 
0 
0 
0 
0 
0 
0 
69 
41 
68 
19 
9.. 
1.5 
48 
18 
82 
13 
87 
11 
89 
0 
0 
0 
0 
60 
52 
68 
59 
Control.. 
82 
18 
92 
8 
100 
0 
0 
0 
0 
0 
69 
41 
68 
19 
5__. 
CS 2 __ 
3 
21 
5 
95 
9 
91 
35 
65 
0 
0 
0 
0 
68 
62 
73 
71 
Control.. 
55 
*45 
59 
*41 
5 
* 95 
0 
0 
0 
0 
81 
60 
82 
53 
210. 
CS 2 . 
6 
21 
e 2 
98 
26 
74 
40 
60 
0 
0 
0 
0 
68 
64 
70 
66 
Control. 
97 
3 
86 
14 
71 
29 
0 
0 
0 
0 
87 
50 
83 
50 
210. 
CS 2 .. 
6 
21 
e 20 
80 
47 
53 
0 
0 
0 
0 
0 
0 
68 
64 
70 
66 
Control.. 
98 
2 
87 
13 
67 
33 
0 
0 
0 
0 
87 
50 
83 
50 
210_. 
CSa.— 
6 
21 
e 5 
95 
35 
65 
10 
90 
0 
0 
0 
0 
68 
64 
70 
66 
210.. 
_do_ 
6 
21 
«6 
94 
60 
40 
71 
29 
0 
0 
0 
0 
68 
64 
70 
66 
Control_ 
90 
10 
97 
3 
62 
38 
0 
0 
0 
0 
87 
50 
83 
50 
.do_ 
96 
4 
90 
10 
75 
25 
0 
0 
0 
0 
87 
50 
83 
50 
300_ 
Liq. HCN_ — 
1.8 
24 
49 
51 
68 
32 
0 
100 
0 
0 
0 
0 
70 
62 
70 
45 
300_ 
.do__ 
1.8 
24 
38 
62 
56 
44 
0 
0 
0 
0 
0 
0 
70 
62 
70 
45 
300_ 
_do.. 
1.8 
24 
52 
48 
20 
80 
0 
100 
0 
0 
0 
0 
70 
62 
70 
45 
Control_ 
92 
8 
84 
16 
88 
12 
0 
0 
0 
0 
85 
51 
92 
44 
150_ 
Liq. HCN..„ 
3.5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
75 
62 
80 
58 
Control.. 
94 
6 
94 
6 
83 
17 
0 
0 
0 
0 
83 
64 
82 
54 
150.. 
Liq. HCN.... 
3.5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
75 
62 
80 
50 
Control. 
90 
10 
82 
18 
75 
25 
0 
0 
0 
0 
83 
64 
82 
54 
150. 
Liq. HCN.... 
3.5 
48 
0 
100 
0 
100 
0 
100 
0 
0 
0 
0 
75 
62 
80 
50 
Control.. 
85 
15 
83 
17 
50 
50 
0 
0 
0 
0 
83 
64 
82 
54 
o- One hundred weevily beans were placed in each of a number of cotton-stoppered vials and the vials 
placed in bags of beans in different parts of the fumigator. A like number of weevily beans were removed 
to the laboratory for controls. 
b Became heavily infested with mites, Pediculoides ventricosus, before they could be dissected. 
e Six pounds of CSa was placed in three shallow pans. In 1.2 hours it was necessary to remove 31 bags; 
then 1£ pounds of CS 2 was added, and the fumigator was closed after being open less than 5 minutes. 
Results should be discarded. 
Table VI shows that all stages of Bruchus quadrimaculatus contained within 
the black-spotted cowpeas were killed by fumigation with 31 pounds of carbon 
disulphide per 1,000 cubic feet in a 29-inch vacuum for 1 hour at 82° F., with 
2 pounds of liquefied hydrocyanic acid per 1,000 cubic feet for 48 hours at 64° to 
92° F., and with 1.3 pounds of liquefied hydrocyanic acid at 58° to 91° F. for 
90 hours. The use of 3.4 pounds of sodium cyanide in fumigation with hydro- 
cyanic-acid gas by the pot method at 69° to 82° F. was also 100 per cent effective* 
