2 BULLETIN 1313, U. S. DEPARTMENT OF AGRICULTURE 
and the Baltimore & Ohio at Locust Point, Md., when cars are isolated and 
protected, until some other satisfactory suitabie substance can be provided, and 
further, that each carrier, member of this association, shall issue, without delay, 
necessary instructions prohibiting its use. 
The following resolution was also adopted at the same time by this 
association: 
That because of the presence of bran bug and weevil in grain and the great 
danger being done thereby, the chairman of this association communicate with 
the Bureau of Agriculture, Washington, D. C., advising of the action taken by 
this association and recommending that such investigations as may be necessary 
be made by the Government to produce a substance for this purpose which can be 
used with safety. 
The investigation reported in this bulletin was undertaken because 
of the action taken by these railroad officials. 
Carbon tetrachloride, hydrocyanic acid gas, sulphur dioxide, 
chloropicrin, naphthalene, phosgene, arsine, cyanogen chloride, and 
many other substances have been tested as fumigants for grain 
weevils by various investigators, who have reached the followin 
conclusions: Carbon tetrachloride is imeffective under practica 
conditions; hydrocyanic acid gas fails to kill weevils very far below 
the surface of the grain; sulphur dioxide has. low toxicity, injures 
ironwork, destroys the germinating power of wheat, makes a sticky 
dough (4), and retards fermentation, the bread obtained being heavy 
and unfit for consumption; carbon dioxide is effective only in tightly 
sealed containers and at relatively high concentrations; chloropicrin 
shows promise of being a practical fumigant, but is not yet com- 
mercially available; naphthalene is not very effective and has an 
objectionable odor; phosgene is poisonous to man, comparatively 
nonpoisonous to insects, and, because of its high vapor pressure, 
difficult to control; the toxicity of arsine to insects is comparatively 
low; the effect of cyanogen chloride as an insecticide is practically 
the same as that of hydrocyanic acid. 
It is evident, therefore, that there is great need for a fumigant 
which will be effective against injurious insects in wheat and other 
cereals and also noninflammable and nonexplosive and neither 
dangerous nor highly disagreeable to those who handle it. The 
object of the investigation here reported was to discover such a 
fumigant, which could be used in place of carbon disulphide. In 
connection with this investigation, much information on the relation 
of the chemical constitution of compounds to their toxicological 
action on insects was acquired. 
EXPERIMENTAL PROCEDURE 
The rice weevil (Sitophilus oryza L.), the flour weevil (Tribolium 
confusum Fab.), and the granary weevil (Sztophilus granarius L.) were 
used in most of the tests, and the Indian meal moth (Plodia inter- 
punctella bn.) was used in a great many. Adult insects of the 
weevils and the larve of the Indian meal moth were used. 
The first series of experiments (Tables 1 and 2) were conducted 
in the apparatus described by Neifert (1/8). Four-liter glass jars, 
containing 10 to 20 live weevils of each species tested, were filled 
with a mixture of air of 40 per cent relative humidity and the vapor 
of the compound to be tested. After standing for 24 hours at room 
temperature (21° to 32° C.), the percentage of dead weevils -was 
determined. (All specimens were examined after 24 hours, and 
also after 48 hours, to avoid reporting as dead those which might 
