PARA-DICHLOROBENZENE AS AN INSECT FUMIGANT. 3 
DIFFUSION OF THE VAPOR. 
Para-dichlorobenzene is very volatile and the vapor is extremely 
heavy, being more than five times that of an equal volume of air and 
more than twice as heavy as carbon bisulphid vapor. Although it 
diffuses quite rapidly through the air, as evidenced by the perception 
of its odor, the vapors will, like carbon bisulphid, tend to work 
rapidly downward, outward, and eventually upward. From the fore- 
going fact it is ascertained that the greater density of vapor is at the 
lower levels. This property is obviously very beneficial when para- 
dichlerobenzene is used as a fumigant for bags of grain, stored 
products, carpets, and rugs, and in all cases where it is desirable to use 
a gas that will penetrate the lowest levels and force its way into 
cracks and crevices in floors, walls, and similar locations. 
DIRECTIONS FOR USING. 
Para-dichlorobenzene is applied in most instances in the same 
manner as camphor and naphthalene. It is not, however, necessary 
to sprinkle it around in corners or over rugs and other material, as is 
often the case with camphor and naphthalene, but merely to expose a 
sufficient quantity in one or two open or partially cpen receptacles, 
placed over, or higher, than the infested cases, goods, and material 
which require fumigation. 
HOW PUT UP AND COST. 
Para-dichlorobenzene at the present time is sold in 5, 10, 25, 50, 
and 100 pound and barrel lots, the prices for which are as follows: 
23 cents per pound, in 5, 10, and 25 pound lots. 
18 cents per pound, in 50-pound lots. 
17 cents per pound, in 100-pound lots. 
15 cents per pound, in barrel lots. 
If any considerable quantity is to be used, it is much betterto 
purchase of some wholesale druggist or direct from the manufacturers. 
APPLICABILITY TO VARIOUS INSECTS. 
Para-dichlorobenzene is applicable to many insect pests living 
under various conditions and environment, and therefore requires 
specific methods of application, and, unlike carbon bisulphid, it is at 
the present time used only indoors and in other places where its 
vapors can be closely confined. As there is a great variation in the 
tenacity of life among insects, the existing conditions should be care- 
fully noted before para-dichlorobenzene is applied. 
Beetles, such as the rice weevil (Calandra oryza L.), granary weevil 
(Calandra granaria L.), the confused flour beetle (T’ribolium con- 
fusum Duv.), the cadelle (Tenebroides mauritanicus L.), the yellow 
