4 
Although the larva prefers flour or meal, it wiil attack grain when 
the former are not available, and it flourishes also on bran and pre- 
pared cereal foods, including buckwheat, grits, and crackers. It lives 
also in the nests of bumblebees and in the hives of the honey bee. 
FIRST USE OF HYDROCYANIC-ACID GAS AGAINST INSECTS IN STORED 
PRODUCTS. 
The use of hydrocyanic-acid gas as a remedy for insects in mills 
and other inclosures where grain, flour, and similar products are 
stored was first suggested by the late W, G. Johnson in the American 
Miller for March, 1898, the incentive for its employment having been 
an invasion of cockroaches in a mill in North Carolina. 
The first test of this method as a means of destroying insects in 
stored products was probably that made by the writer the same year.* 
Additional experiments were soon afterwards made in conjunction 
with Mr. Pratt and the cost and the advantages and disadvantages 
carefully weighed, with the resulting conclusion that since hydrocy- 
anic-acid gas is infinitely more dangerous to human life than bisulphid 
of carbon, as well as more expensive, its employment as a fumigant for 
ordinary insects injurious to stored products was less desirable. On 
this account no publication was made of the results nor was it, until 
recently, recommended to the numerous persons who inquired. for 
remedies for mill pests. Soon after this first experiment a test to 
determine the availability of this gas against the Angoumois grain 
moth was made on a larger scale but with very imperfect success.® 
aMarch 5, 1898, the writer, with Mr. F. C. Pratt, then working under his direc- 
tion, fumigated a lot of dried grain infested by the rice weevil (Calandra oryza L.) 
and a leguminous seed affected by a Bruchus or seed weevil, the material being placed 
in a moderately tight fumigating box. The cyanid of potash was purchased in open 
market and was used at the rate of 2 ounces to each 100 cubic feet. A quantity of 
acid slightly in excess of the salt was employed with twice that amount of water. 
The experiment began at 4 p. m. Saturday and was conducted in a building in which 
the temperature was usually from 70° to 76° F. The following Monday morning at 
7.30, when the door was opened for airing, no odor was perceptible, and only a very 
slight trace of gas could be detected a half hour later when the box lid was removed. 
As a result all the seed weevils (Bruchus) loose in bags were found dead and all of 
the rice weevil, except a very few individuals, which revived after a few hours— 
less than 0.1 per cent—were killed. 
b A lot of paddy or unhulled rice infested by this moth was desired to be fumigated 
and was placed in what appeared to be a nearly air-tight inclosure, a room specially 
prepared for the purpose. The cyanid was prepared in the usual way and was used 
at a strength of about 1 ounce to 100 cubic feet, but after the fumigation the insects 
were seen to be flying freely about the fumigating room. See Bureau of Entomology 
Cir. No. 46, entitled, ‘‘ Hydrocyanic-acid Gas against Household Insects,’’ by L. O. 
Howard, first issued in 1902, revised edition February 20, 1907. Note what is said 
in the footnote on page 2. 
[ Cir. 112] 
