Oct. 16, 1916 
Effects of Nicotine as an Insecticide 
93 
They were covered more or less with white “wool,” which was less con¬ 
spicuous after being wetted by the spray. Five minutes later the aphids 
stood up, began to move their legs, and most of them were comparatively 
active for a few moments. They removed their beaks from the leaves, 
moved about considerably by lifting the legs nervously, and their peculiar 
jerky movements became more conspicuous. Later they were more 
quiet and the legs became paresized, the hind legs being affected first, 
the middle legs next, and the front legs and antennae last. At this stage 
the hind legs generally are totally stricken with motor paralysis. When 
paresized, many of the aphids fell from the leaves, and for a few moments 
they seemed to be recovering from their stupor; but they finally died. 
However, all of those that fell from the leaves lived several moments 
longer than those that remained on the leaves. When almost inactive, 
the aphids fell either over on their sides or on their backs and were com¬ 
pletely helpless. The last signs of life were twitchings of the tarsi and 
slight movements of the antennae. Before death, the bodies of the aphids 
appeared perfectly dry. When dead, the legs are usually folded and are 
stiff. During the various stages of paralysis, it was common to see 
small drops of clear and dark fluids issuing from the cornicles and anal 
openings. 
( c ) insects sprayed with solution op nicotine sulphate 
Many aphids on leaves of the Carolina poplar (Populus deltoides ) were 
heavily sprayed with a solution of nicotine sulphate, made in the propor¬ 
tion of 1 ounce of the nicotine sulphate to % gallon of water, this being 
1 part of the insecticide to 64 parts of water, which is 12^ times as strong 
as recommended for the more resistant sucking insects, such as the black 
aphis and woolly aphis. This nicotine sulphate is guaranteed to be at 
least 40 per cent nicotine, and the analysis of this sample showed that it 
contained a fraction more than 40 per cent. Four hours after being 
sprayed, all these aphids were apparently dead. 
In practical work nicotine as an insecticide is rarely used for caterpillars 
and probably never in the form of spray for the imagoes of coleopterous 
and hymenopterous insects, but it was desirable to ascertain how nicotine 
affects various kinds of insects and to obtain material for the study of the 
tissues after the insects had died of nicotine poisoning. For this reason 
various kinds of insects were heavily sprayed with the above solution. 
An hour elapsed before the large caterpillars of the catalpa sphinx 
(i Ceratomia catalpae Bdv.) died; however, a much weaker solution 
(1 :1,200) apparently killed the small caterpillars (6 to 10 mm. in length) 
of the same moth in five minutes, and the same was true of an extract 
made of powdered tobacco and water (50 gm. of tobacco boiled in 1,000 
c. c. of water). The stronger solution of the nicotine sulphate quickly 
killed the small caterpillars of Atteva aurea Fitch, and of Datana sp., 
but it was not so effective on the larger larvae of the lesser wax moth 
