94 
Journal of Agricultural Research 
Vol. VII, No. 3 
(Achroia grisella Fab.) and on bagworms, larvae of Thyridopteryx epheme¬ 
rae j or mis Haw. Of the four adult blister beetles (Epicauta pennsylvanica 
DeG.) sprayed, only three died, and worker bees could not be killed by 
spraying them. 
From the foregoing it is thus seen that there is considerable difference 
in the responses of various insects to nicotine spray solutions. The 
youngest and smallest individuals of any given species always succumb 
first and some imagoes, such as bees, can not be killed at all. 
3.-NICOTINE AS A FUMIGANT 
The following apparatus was devised: To the neck of a 50 c.c. retort 
supported on a ring stand was connected a piece of rubber tubing 12 
inches in length, with its free end projecting into a battery jar 9 inches in 
diameter and 12 inches in height. The jar was covered with a piece of 
glass. 
(a) APHIDS FUMIGATED WITH PURE NICOTINE 
Carolina poplar leaves bearing many aphids {Aphis populifoliae) were 
supported in a bottle, and the bottle with its contents was placed inside the 
battery jar so that the aphids did not touch the sides of the jar. Twenty- 
five c. c. of pure nicotine were poured into the retort, which was then 
heated gently. The free end of the tubing was removed from the battery 
jar, and the heat was still applied. Brownish fumes soon arose from the 
nicotine; they immediately condensed upon striking the upper, colder 
portions of the retort, which soon became too warm to condense them. 
Other fumes then passed into the neck of the retort, where they were 
likewise immediately changed into liquid, which ran in little streams back 
into the retort. The rubber tubing was next warmed by the fumes. 
As soon as drops of the liquid ceased to fall from the free end of the tubing 
the fumes were passing freely from this end. The tubing was then inserted 
into the battery jar. At once the aphids began to squirm, and the jar 
was soon filled with dense fumes. At this instant the burner was removed 
from under the retort, whereupon the fumes began to condense. A 
little later small streams of the liquid ran down the sides of the jar, and 
small drops collected on the underside of the glass cover. The leaves and 
the aphids seemed to be covered with a fine spray. 
So far as could be observed through the dense fumes, the behavior of 
these aphids was similar to that of sprayed aphids. Before dying 
many of them dropped from the leaves. Most of them appeared dead 
within three minutes after the introduction of the fumes; two minutes 
later still all of them were dead. 
The preceding mode of procedure has been described in detail in order 
to make evident the ease with which the liquid can be applied by fumi¬ 
gating to cool surfaces with which the vapors may come in contact. 
Since the temperature of insects is practically the same as that of the 
