THE LESSER GRAlK-BORElt. 37 
The results show that this grain-borer appears to be possessed of a 
lower degree of vitality, or at least of less resistant power to both of 
these gases than are the other classes of grain-feeding insects which 
have been (mentioned. These series of experiments are also of value 
as bearing out the writer's experience in the experimental and prac- 
tical fumigation of inclosures against insects in low temperatures, 
substantiating conclusions made years ago, that insects in general 
are not so susceptible to poisonous gases while torpid as when they 
are exposed to a higher temperature and are consequently normally 
active. 
Experiments by D. K. McMillan. 
BISULPHID OF CARBON. 
Experiments Nos. 1 and 2. — At Houston, Tex., December 2 and 3, 
a bin of Japan rough rice badly infested with the lesser grain-borer 
and other species was treated in a mill with carbon bisulphid by 
pouring the liquid upon a large mass of empty sacks within another 
sack and hanging in the bin just above the grain. The bin con- 
tained about 2,500 bushels and was about one-third full. 
The top could not be closed in any practicable way. 
A short time after putting in the carbon bisulphid the fumes 
were coming out of the cracks in the sides and out of the bottom, 
which was 8 feet above the floor of the mill. Two experiments were 
made, with an exposure of 24 hours, as follows : 
1 gallon of carbon bisulphid to 2,500 bushels of grain. 
2 gallons of carbon bisulphid to 2,500 bushels of grain. 
A large quantity of grain from the bottom of the bin showed prac- 
tically all insects alive. As the bin was not tight enough and the 
weather was below 45° F. during this time, these experiments were 
unsuccessful. 
A series of experiments with carbon bisulphid was conducted at 
Beaumont, Tex., December 5 to 7, upon various rice-mill products 
infested principally with this species. The tests were made with 
50-gallon glucose barrels, which were very tight from the sirup, and 
tight covers of car paper were fitted over the tops and tied firmly. 
Carbon bisulphid in the following proportions was used : 
Experiment No. 
Proportion. 
Exposure. 
3 
2 pounds to 1 000 cubic feet 
Hours. 
24 
4 
4 pounds to 1,000 cubic feet 
24 
5 
5 pounds to 1,000 cubic feet.. 
24 
6 
6 pounds to 1,000 cubic feet 
24 
7 
8 pounds to 1,000 cubic feet . 
94 
8 
10 pounds to 1,000 cubic feet 
24 
9 
15 pounds to 1,000 cubic feet 
24 
10 
20 pounds to 1,000 cubic feet 
24 
