30 Farmers’ Bulletin 1275. 
240-pound sacks, and stacked as shown in Figures 26 and 27, were 
almost perfectly protected by fumigation. It has been found in the 
fumigation of warehouses, sometimes as large as 150 by 150 by 20 feet, 
and containing as many as thirty thousand 240-pound sacks of chick- 
peas, that hydrocyanic-acid gas can be depended upon to eliminate 
infestations almost completely. Fumigation with this gas for the 
control of bean and pea weevils has proved so satisfactory that its use 
is now an established practice with certain firms. The dosage should 
be increased from 1 to 24 pounds of cyanid for each 1,000 cubic feet 
of space to be fumigated. Since it is extremely poisonous, 
hydrocyanic-acid gas should be used only by responsible 
persons who are thoroughly informed on the subject of 
fumigation. As the gas is lighter than air and readily escapes, 
does not injure the seeds for planting or for food, injures no ware- 
house equipment, and is noninflammable when mixed with air in 
the proportions used in fumigation, it lends itself for use in almost 
any warehouse section if the fumigation is properly timed and 
supervised. For further information secure from this department 
' Farmers’ Bulletin 699 and Department Bulletin 872. which give full 
particulars of procedure. 
HEAT. 
Heat as a means of killing weevils in legumes is growing in favor. 
Small quantities of seed grown on the farm or in the town garden 
can be treated by placing them in an oven after they have been spread 
rather thinly in shallow pans and heating them to 120° to 145° F. 
for several hours. An old remedy is to dip seeds into boiling water 
for one minute. Holding seeds in boiling water for more than one 
minute will injure their value for planting purposes and exposure 
for even one minute has been known to affect germination. On 
removal they should be spread out immediately and dried rapidly. 
Weevil development in large quantities of beans, peas, and cow- 
peas can be stopped by a process known as kiln-drying. This process 
consists in heating the seeds to a temperature of 120° to 145° F., or 
higher, while they are being passed through a machine called a drier. 
This treatment not only removes a portion of the moisture in the 
seeds but also kills all insects in them. The loss of moisture may be 
an item of importance if sales are made by the pound, yet investi- 
gators claim that seeds containing 20 per cent of moisture or less are 
not easily infested by weevils, hence excessive drying with the heat 
not only kills the weevils but renders seeds less susceptible to re- 
infestation. 
The embryos of the common bean weevil are killed when exposed 
to 125.6° F. for 10 minutes; the newly hatched larvee die in 7 minutes 
