Oct. 16, 1916 
95 
Effects of Nicotine as an Insecticide 
air surrounding them, it seems evident that the nicotine fumes would be 
condensed upon striking the integuments and tracheal walls of the 
insects fumigated. 
The preceding experiment was repeated by using aphids (Aphis 
rumicis L.) on nasturtiums. Small pots containing these plants were 
placed inside the battery jar. Five minutes after introducing the fumes 
all the aphids were dead. 
(b) INSECTS FUMIGATED WITH 40 PER CENT NICOTINE-SULPHATE SOLUTION 
The preceding experiments were repeated by fumigating the follow¬ 
ing insects with a 40 per cent solution of nicotine sulphate: Aphids on 
nasturtiums (Tropaeolum majus) and those (Myzus persica Sulz.) on 
potato plants (Solanum tuberosum ), coccids (Orthezia insignis Dougl.), fall 
web worms (caterpillars of Hyphantria cunea Dru.), larvae of potato 
beetles (Lepiinoiarsa decemlineata Say), imago house flies (Musca domes - 
tica T.) and worker honeybees (Apis mellifica T.)* 
The aphids and coccids died a few minutes after the introduction of 
the fumes, and the plants which bore them were also affected consider¬ 
ably by the fumes. The leaves on the potato plants soon wilted, and 
some of them finally turned brown. They emitted a comparatively 
strong nicotine odor for several days, and even a very faint nicotine odor 
was perceptible 15 days after the plants were fumigated. 
The fall webworms and potato-beetle larvae (two-thirds grown) were 
not so easily killed, although after being confined for a period of 15 or 20 
minutes in dense fumes, they die. While dying, the caterpillars wriggle 
about considerably and exude a yellowish fluid from the mouths. Bees 
die in the same length of time, but house flies do not succumb so readily. 
Bees, when apparently dead, often revive if they are removed from the 
jar to fresh air. 
The preceding experiments indicate that nicotine as a fumigant kills 
insects by paralysis and that part, if not all, of the fumes, which strike 
the integuments and which pass into the tracheae of the insects, are 
condensed before they enter the various tissues. On page no it is 
shown that the nicotine never passed far from the tracheae into the 
tissues. This supports the view that nearly all of the fumes in the 
tracheae were changed into liquid which did not pass readily through 
the tracheal walls. It is also seen that the most delicate insects yield 
first to nicotine fumes. 
4.- NICOTINE ODOR AND VAPOR 
To determine the effects of nicotine odor on insects, leaves were either 
sprayed with or dipped into nicotine spray solutions. Their stems were 
then inserted into bottles of water which were placed in the sun or in 
front of an electric fan. The leaves were alwavs left in the current of 
