FUMIGATION AGAINST GRAIN WEEVILS 25 
of epichlorohydrin equivalent to 2.06 pounds per 1,000 cubic feet, 
combined with carbon tetrachloride at the rate of 10 pounds per 
1,000 cubic feet, did not kill all of the insects in every test. 
The compounds consistently causing 100 per cent mortality in the 
small-scale tests in wheat (Tables 4, 5, and 6) are shown in Table 7. 
TaBLeE 7.— Most effective fumigants for weevils (based on results in Tables 4, 5, and 6) 
| 
: Mini- Mini- 
mum mum 
concen- concen- 
tration tration 
consist- consist- 
a ently = ently 
es “ causing est < causing 
No. Fumigant 100 per || No. Fumigant 100 per 
cent mor- cent mor- 
tality of tality of 
all species all species 
after ex- after ex- 
posure for posure for 
24 hours 24 hours 
Lbs. per Lbs. per 
1,000 1,000 
456 eee Ethylene bromid cee 
‘ ithylene bromide______________- 6.2 
462 \ethyl bromide-__----.---------- 18.2 439 ee tetrachloride_____________ 10.0 
629 VaEeho Dromidests. -8. 5s2 4 Ves 4.5 603 
630 |f Carbon tetrachloride____________- 10. 0 604 |{ Ethylene bromide______________- 8.0 
g15 |{Ethy! bromide__-_______-..__---- 4.51) 681 |{Carbon tetrachloride_____-.___--- 8.0 
616 Carbon disulphide______________- 22, 632 
Carbon tetrachloride_____________ 10. 0 589 |\ Ethylene bromide__________-___- Dao 
Hii ylebromide@sean = | eee a se 4.5 || 590 |f Carbon tetrachloride______-______ 12.0 
611 |} Carbon disulphide__.____________ 22 594 |) Ethylene bromide______________- 5.3 
612 |)Carbon tetrachloride_____________ 10.0 597-|;Chiorobenzene..2_- 2 2 a 10.0 
Ethylene bromide-_-_____________- 5.3 598 |} Carbon tetrachloride_____________ 10.0 
5OOnE thy bromidest= ===. ~s2 7 13. 2 || 472 ee pee Se ee ae 2.9 
600 |f Ethylene bromide_______________ 5. Sill ae Carbon tetrachloride____________- 10.0 
BAOTIVE Tey EON Got ibayg 445 ean HOLTNAtE ss ee wee es ED 
oe By sommate eSee eee e e e 36: 1 te Carbon tetrachloride___.._______- 10.0 
5 thy Ubromide 2 2622 ae IE? : F 
586 |f Methyl formate.............. = 3.5 || 547 \carbon disulphide __-----_---__-- 6.4 
With the exception of carbon disulphide, the most economical 
fumigant at 1924 prices, is the combination of ethyl formate with 
carbon tetrachloride. (The ethyl acetate-carbon tetrachloride mix- 
ture,> which was the most suitable and economical fumigant of all 
those tested, was not tried on a small scale.) 
IN BOX CARS 
Many tests were also carried out in box cars of grain. Weevils 
in perforated pill boxes (10 in each box) were planted at 10 different 
levels in the grain in a box car, by putting the boxes in the compart- 
ments of a grain sampler, which was then plunged into the grain at 
an angle of about 45°. 
The fumigant was applied to the grain by sprinkling the liquid 
over the surface from a small sprinkler-top watering can as quickly 
as possible. The door of the car was then closed and sealed. 
Twenty-four hours later the pill boxes were withdrawn and the 
number of dead weevils was determined (Table 8). (The more toxic 
substance, with its concentration, is given first; the less toxic sub- 
stance, used principally as a diluent, with its concentration, is given 
next in Table 8.) 
5 The use of ethy] acetate and ethyl] acetate-carbon tetrachloride mixture was suggested by R. C. Roark. 
