10 CIRCULAR 386, U. 8. DEPARTMENT OF AGRICULTURE 
directed, and is heavier than air. It is noninflammable and nonex- 
plosive. It kills adults and larvae of the wax moth but is not 
effective against the eggs. 
In fumigating with paradichlorobenzene, the supers should be 
stacked as tightly as possible and the cracks between supers covered 
with gummed paper strips (fig. 5). A generous handful of the crys- 
tals should be placed on the top of the frames of the top super and 
the cover put tightly in place. The crystals may be sprinkled di- 
rectly on the top bars of the frames, as in figure 5, or put on a piece 
FIGURE 5.—Supers loaded with comb ready for fumigation. The joints are sealed with 
gummed paper tape, and the crystals of paradichlorobenzene have been sprinkled 
heavily over the top bars. 
of paper laid on the top bars. Since the gas is nonpoisonous and 
not disagreeable, treatment may be made in ordinary storage without 
taking the infected material out of doors. At intervals during the 
storage season the covers of the stacks should be raised, and unless 
some are still present, more crystals added. 
Paradichlorobenzene is at present as cheap as any of the materials 
mentioned in this circular, with the exception of sulphur, and is by 
far the easiest and least dangerous to use. The crystals last for some 
time, since they volatilize slowly, and not only kill the larvae and 
adults first present and the larvae as they hatch from the eggs, but 
repel moths from outside which might otherwise enter and start a 
fresh infestation. Paradichlorobenzene is most effective at tempera- 
tures above 70° F. and volatilizes more rapidly as the temperature 
rises. Inspections of stored materials should be made at intervals 
of 2 or 3 weeks, depending on the temperature of the storehouse and 
the prevalence of adult moths, 
