162 FUMIGATION METHODS 
difference in the resisting powers of various species of 
insects is so slight we generally recommend for indoor 
fumigation the use of the 0.25 gramme formula. Un- 
der no circumstances should a less amount be used, 
unless specifically designated by an expert. 
Some beetles require the full strength to destroy 
them in most enclosures. This is particularly true of 
the bolting-cloth beetle, Tenebroides mauritanicus, and 
its young, a small, flat, whitish, greasy-looking crea- 
ture, about one-third to one-half inch long, familiar to 
millers ; the flour beetle, 77zbolium confusum, and its 
young ; the grain weevils, Calandra granaria and C. 
oryza,; and the American meal worm, 7enebrio molitor. 
In fact, nearly all the beetles commonly found in mills 
and other enclosures where farinaceous foods are stored 
or manufactured are not as easily killed with the gas 
as moths and their young. Bearing these facts in 
mind, it is, therefore, best to use the gas in accordance 
with the 0.25 gramme formula. 
Estimating chemicals.—The amount of cyanide 
necessary for any enclosure is determined in terms of 
grammes per cubic foot of space enclosed. ‘To deter- 
mine the exact amount of cyanide necessary to fumi- 
gate a room, car, ship, or building of any kind, the 
cubic contents must be accurately computed. As an 
example, a room 20 x 30x 10 feet contains 6,000 cubic 
feet of air space. To estimate the amount of cyanide 
required for this enclosure, multiply 6,000 by 0.25 ; 
thus: 6,000x0.25—=1,500 grammes. ‘To reduce this 
to ounces, divide by 28.35, as there are 28.35 grammes 
in an ounce; thus: 1,500+ 28.3553 ounces, the 
exact amount of cyanide needed for the enclosure. It 
