42 INSECTS AFFECTING STORED PRODUCTS. 
of Tribolium were found still alive. The number of live specimens 
was estimated at about 5 per cent. The examination was continued 
for two hours, taking samples from all parts of the room, when the 
number that failed to succumb seemed to decrease somewhat, for 
sample after sample was taken from the more exposed pockets and 
no live specimens were observed, with exception of grain from sacks 
taken from the interior of the stack of pockets. From near the 
center of these pockets a few specimens were vet fully active. No 
other species was observed alive, but all appeared dead with the 
exception of Tribolium navale. 
Experiment No. 16. — At 5 p. m. December 21 another charge was 
made, using the same amount of sodium cvanid and sulphuric acid as 
in previous experiments (20 ounces of cyanid to 1,000 cubic feet), 
and left until December 24. The door was opened at the same hour 
and the inspection begun, paying special attention to the clean rice 
and the bran where Tribolium was most abundant. At this time no 
live specimens were found at all, but the dead bodies were numerous. 
The conditions for fumigation work were not the most favorable; 
the temperature was too low to secure the best results, ranging from 
49° F. to a little above 60° F. the whole time the experiments were 
on. It has been demonstrated that better results are obtained at a 
temperature upward of 65° F. At this time the weevils are more 
active and succumb more readily to the fumes. 
Experiment No. 17. — Later, December 26, at 67° to 71° F. a sample 
of rough and chicken-feed rice treated with hydrocyanic-acid gas for 
a period of 24 hours had yet alive one specimen of Calanclra oryza, 
two specimens of Rhizopertha clominica (hundreds of dead bodies), 
and several of Tribolium, navale. On the same date samples of rough 
rice, chicken-feed rice, rice bran, and clean rice were examined to 
ascertain if any living weevils were yet present. From one cigar box 
of rice bran and rough rice 5 beetles of the Tribolium were found, 
quite active. 
Experiments by the Writer and by Messrs. Popenoe and Jones. 
bisulphid of carbon. 
Experiment No. 18. — December 31, 1910, at Washington, D. C, a 
lot of Rhizopertha clominica in cracked rice, together with other 
insects, was placed in a bag and exposed to the fumes of bisulphid 
of carbon in one of the fumigating boxes of the type much used in 
the Department of Agriculture for fumigating seeds, the reagent 
being used at the minimum strength for such purpose, or at the rate 
a Among this same material three of Silvanus were alive, while there were a 
number of dead bodies each of Tribolium and Silvanus. In the clean rice, 
where both species were more numerous, all were dead. 
