Apr. 26, 1924 
Fumigation of Bean Weevils 
353 
Table VI.— Effect of fumigation of weevils , Bruchus quadrimaculatus, within 
black-spotted cowpeas 
Material used 
Dosage per 1,000 cubic 
feet 
Exposure 
Killed 
Eggs 
Larvae 
Pupae 
Adults 
Tem¬ 
pera¬ 
ture 
Humid¬ 
ity 
bo 
a 
3 
>* 
A 
g 
•?! 
o 
03 «h 
•?| 
© 2 
a w> 
o 
o 
S-l 
3 
Pm 
<X> 
bo 
S-i 
03 
1 
a 
Emerged 
before fu¬ 
migation 
a 
1 
1 
s 
a 
a 
a 
§ 
a 
g 
a 
s 
a 
:§ 
s 
CS 2 and 29-inch vacuum_ 
Do__ 
Liq. HCN... 
Do__ 
Control.. 
Lbs. 
31 
31 
2 
2 
Hrs. 
1 
1 
48 
48 
P. ct. 
100 
100 
100 
100 
172 
154 
157 
210 
51 
23 
34 
28 
28 
171 
39 
113 
25 
12 
8 
20 
17 
23 
64 
9 
78 
21 
6 
10 
6 
5 
18 
15 
7 
48 
18 
15 
13 
20 
26 
17 
18 
17 
43 
17 
25 
36 
27 
25 
13 
28 
24 
23 
31 
24 
21 
14 
17 
27 
26 
6 
21 
18 
8 
11 
7 
9 
51 
47 
4 
70 
°F. 
82 
82 
92 
92 
92 
92 
91 
91 
82 
O p 
82 
82 
64 
64 
64 
64 
58 
58 
69 
79 
79 
79 
79 
79 
79 
71 
46 
46 
46 
46 
43 
43 
61 
Do__ 
Liq. HCN.. 
Control__ _ 
1.3 
90 
100 
69 
HCN, pot method__ 
«3.4 
48 
100 
a Dosage of sodium cyanide employed to generate the gas. 
The weevils here listed were in all stages from fresh-laid eggs to weevils just 
beginning to emerge at the time they were prepared for fumigation. The vacuum 
fumigation was done at Sacramento and the other at Puente, Calif. The 
fumigated cowpeas and controls were prepared the same day, but those going 
to Sacramento were in transit one day longer than the others and consequently 
more weevils emerged from them before fumigation. The eggs on the fumigated 
cowpeas were counted at the time they were dissected, but the eggs on the 
control were not counted because several weevils had emerged from them, 
thereby removing some of the eggs, and these weevils had also laid numerous 
eggs on the cowpeas before they were dissected. 
On August 28, or 13 days after the first fumigation, the weevils within the 
controls were all killed, because they became infested with mites, Pediculoides 
ventricosus. Although all the weevils were dead at the time they were dissected 
from the cowpeas, the tabulation shows that a marked development of the 
weevils took place within the controls during the 13 days after the others had 
been killed by fumigation. 
In Tables VII and VIII the weevils contained in the first four and the first 
ten controls, respectively, were killed because of mites when they had developed 
13 days after the others were fumigated, while in the other controls the weevils 
were killed after 16 days 7 development. In these, as in Table VI, all weevils 
were dead when they were dissected from the cowpeas. The marked develop¬ 
ment noted in the controls indicates that all stages had been killed immediately 
in the fumigated cowpeas. 
The work of Paddock and Reinhard ( 5) indicates that they killed all eggs, 
larvae, and pupae of Bruchus quadrimaculatus when they used 4 pounds of 
carbon disulphide per 1,000 cubic feet for only 24 hours. 
