94 BULLETIN 1313, U. S. DEPARTMENT OF AGRICULTURE 
EFFECT OF FUMIGATION ON WEEVILS IN THE PRESENCE OF GRAIN 
IN BOTTLES, BOXES, AND BARRELS 
In order to ascertain the action of the compounds as they would 
be used in practical fumigation work, weevils were placed in pill boxes, 
with perforations to permit the entrance of the vapor, and the boxes 
were placed at different levels in grain, usually wheat. The weevils, 
usually about 10 to the box, were exposed to the action of the com- 
pounds for 24 hours, at temperatures from 21° to 32° C. 
One series of tests was carried out in large glass bottles of 19 liters 
capacity (Table 4), another in a wooden box of 100 cubic feet 
capacity (Table 5), and another in a barrel of 6 cubic feet capacity 
(Table 6). The fumigant or mixture of fumigants was applied in all 
these tests by pouring the calculated quantity over the top of the 
grain and then closing the receptacle. The bottle had astopper, the 
barrel had a wooden head, and the box was provided with felt strip- 
ping and a tight-fitting cover, which could be clamped down. 
(In Tables 4 and 5 the more toxic substance, with its concentra- 
tion, is given first; the less toxic substance, used principally as a 
diluent, with its concentration, is given next.) 
TaBLE 6.—Results of fumigation tests°on weevils in grain in barrels (6 cubic feet 
capacity) 
Weevils killed after exposure for 24 hours 
Concen- |Aver-| Bottom of barrel | Middle of barrel | Top of barrel 
No. Fumigant ene mor ER 9 Re ev et 
nt jtali ; : j 
ee ty g S.gra- fe s S.gra- re S.gra- ate 
> - | nar- ol- | nar- ol- | nar- ol- 
ory2a) ius |ium |°7Y7") jus | ium |%Y4! ius | ium 
Lbs. per 
1,000 cu. 
, ft. Pct. | P. cla Pret. SP cts| Poct.| Patt. | eect. |e et ec OL) OP Cl, 
386 | Carbon tetrachloride 15. 0 17 0 0 95 0 0 25 0 0 30 
(75 per cent) and 
turpentine (25 per 
cent). 
387 GOS kid ae bees 30. 0 14 30 0; 100 0 0 0 0 0 0 
394 |. Carbon disulphide __- 7.0 525 |) MOONE = 283 0 SOM eae OF | artOOn tee 60 
409 |_---_- (6 Ko YRS etn - PR ee 10. 0 87 POO; Ese 100 LOO Seas 100 TOO pie See 0 
AlOA S| 22: = GOES esos es eee 10. 0 71 LOGE ie aes 100 7 Ai ya) ee aes 0 LOOn | Ses2— 2 1 
144] Fae Caan Sb oe A ae Se 10. 0 100 100 {a5 23 100 LOO) | eee 100 WOO pose 100 
Ethylene bromide_-__- 3:1 \ 
403 \Carbon tetrachloride. 10.0 100 LOD SS 2 100 OO pero 100 100) | === 100 
Ethylene bromide_-_-__- shal \ y 
431 \Carbon tetrachloride-_- 10. 0 50 50 |------ 50 0 |------ 100 0 |------ 100 
450 | Ethyl bromide__-____-- 9.1 96 100: E22 = © 100 hOOs eee 100 DOE = as 25 
A5Gi|=2= ae nates ee ae weal 22 18. 2 100 100 {2 2 3 100 KOOm eee 100: | === 100 
Epichlorohydrin_-____-_ 1.0 
447 {Carbon tetrachloride 10. 0 } ae AUD PaO Sao MOU OG EUS Gan om ke 
n-Butylnitrite_______- 2.9 \ 
458 Jen tetrachloride_- 10.0 92 50 |------ 100 | 100 |------ 100 100 |------ 100 
1 Barrel made as tight as possible in this test. 
The insecticidal action of a gas is greatly lessened by the presence 
of grain, probably because the grain absorbs miany vapors in large 
quantities and because the grain mechanically interferes with the 
diffusion of the gas throughout the receptacle. For example, in a 
glass vessel containing nothing but weevils and the vapor of the 
compound (mixed with air), epichlorohydrin killed 100 ee cent of 
the insects at a concentration equivalent to 0.23 pound per 1,000 
cubic feet; when the weevils were planted in wheat, a concentration 
