FUMIGATION AGAINST GRAIN WEEVILS 39 
3 out of 15 chlorides tested; the only iodide tested; 1 alcohol out of 
8 alcohols and phenols tested; 3 out of 4 aldehydes tested; 2 out of 
4 ketones tested; both of the chlorine-substituted ketones tested; 1 
of the 2 chlorohydrins tested; 5 out of 9 esters tested; 4 out of 12 
sulphur compounds tested; 1 nitrile out of 5 nitriles and isonitriles 
tested; both of the nitrites tested; 2 out of 8 amines tested; and 
pyridine. 
The relative toxicity of the different classes of compounds can 
not be given because the low volatility of several of those tested 
gave pat very low vapor concentrations. As a class, the hydro- 
carbons showed the lowest insecticidal efficiency, not one of the eight 
tested equaling carbon disulphide in fumigating power. The most 
effective fumigant in the glass-jar tests was epichlorohydrin, which 
killed the rice weevil at a concentration of 0.09 per cent, equivalent 
to 0.23 pound per 1,000 cubicfeet. It was, however, an unsatisfactory 
fumigant in ‘he presence of grain. 
There is no constant relationship between the boiling points and 
the lethal concentrations of the compounds killing 100 per cent of 
the rice weevils after exposure for 24 hours. 
A much greater concentration of fumigant is required to kill 
weevils in wheat than to kill those exposed directly to the vapors 
in glass jars. A still higher concentration is necessary to kill weevils 
in wheat in box cars. Ethyl formate and ethyl acetate were the 
only promising fumigants for grainin boxcars. Theacetate, however, 
costs only about one-third as much as the formate. 
Odoriferous constituents of low volatility from commercial grades 
of ethyl acetate (both the 85 per cent and the 99 per cent grades) 
are carried through from the fumigated wheat to the flour, and 
even to the bread baked from it. A pure grade of ethyl acetate, 
however, leaves practically no odor in the fumigated grain or in the 
bran or shorts made from the grain, and none in the flour or in the 
bread baked from the flour. 
The insecticidal efficiency of ethyl acetate under practical fumigat- 
ing conditions is increased by the addition of carbon tetrachloride. 
The most effective fumigant, other than carbon disulphide, 
against weevils in wheat, in grain cars, under practical fumigating 
conditions, is a mixture of about 40 volumes of ethyl acetate and 
about 60 volumes of carbon tetrachloride. It is noninflammable at 
ordinary temperatures. The proper dosage of this mixture for 
fumigating box cars is about 45 pounds per 1,000 cubic feet. Both 
the ethyl acetate and the carbon tetrachloride must be tested to make 
sure that they are free from odoriferous constituents of low volatility 
before they are used in grain fumigating. 
LITERATURE CITED 
(1) Attson, A. M. 
Beetles damaging seasoned timber—IV. Methods of treatment. Jn 
Timber Trades Journal (1922), 91:1170-1. 
(2) BERTRAND, GABRIEL, and RosENBLATT, M. 
Action toxique comparée de quelques substances volatiles sur divers 
insectes. Jn Compt. rend. (1919), 168:911-13. 
(3) Burmeister, HERMANN. 
A manual of entomology, translated by W. E. Shuckard, London (1836), 
p. : 
(4) Carteret, M., and Carteret, G. 
Sur l’altération des farines et céréales par SO,. Jn Bull. soc. chim. 
(1909), series 4, vol. 5, p. 270-2. 
