- 508 - 
The action of nicotine on insects is to cause a complete 
paralysis of the motor centers brought about by a condensation 
of the vapor upon the walls of the tracheae, and subsequent ab- 
sorption of the nitrogen atom by the nitrogen fat compounds that make 
up the nerve tissue, with the result that further absorption of oxygei 
is stopped and the insect is killed. Until recently, it was thought 
that nicotine solutions passed into the tracheae and penetrated 
into the integuments of insects, but it is now known that it is 
only the fumes from fumigants and the vapors from evaporated spray 
solutions and odoriferous particles from dusts which pass into the 
tracheae and are widely distributed to all the tissues. Nicotine 
is far less certain in its action when used as a stomach poison 
against biting insects, on which it, acts mainly as a repellent 
(p. 403). 
•McGOVRAN, E. R. (2156) 
1929. INCREASING THE EFFECTIVENESS OF THE NICOTINE INSECTICIDAL UNIT 
CHARGE. Jour. N. Y. Ent . Soc . 37 (4): 513-531. [Abstract in Rev. 
Appl. Ent. (A) 18: 278. 1930. J 
Distilled water or distilled water carrying nicotine extract, 
having a surface tension of 40 or more dynes per cm. did not pene- 
trate into the tracheae of the honey bee, even though the integu- 
ment was thoroughly wetted. Addition of from 0.2 to 2 percent 
sodium oleate so reduced the interfacial and surface tensions as 
to permit this to occur. Sodium oleate soap was more effective 
than fish-oil soap. Free nicotine was more effective than nicotine 
sulphate against the cabbage aphid ( Brevicoryne brassicao L.) when 
used with soap. Soap greatly reduced the lethal concentration of 
nicotine to the green apple aphid ( Aphis pomi DeGr.) TThen sodium 
oleate is used at a strength as great as 0.5 percent, the amount 
of nicotine necessary to kill aphids at summer temperature- is very 
small. 
STSLLT7AAG, F. (2157) 
1929. ON THE ACTION OF NICOTINE. Anz. Schadlingsk. 5(3): 33-39. [ Ii 
German. Abstract in Rev. Appl. Ent. (A) 17: 462. 1929.] 
The pharmacological effect of nicotine insecticides on the 
larvae of the vine moths ( Clysia ambiguella Hb. and Polychrosis 
botrana Schiff.) in Germany showed that the effect of the poison 
is typically a paralysis of the nerves. None of the various prepara- 
tions acted as a corrosive poison. Kost cases of poisoning occurred 
when the poison was taken by the mouth, pure nicotine sulphate being 
the most active constituent of the insecticides tested. The small 
doses used in viticulture, however, only gave poor results without 
a carrier, the best being a neutral or slightly alkaline soap, at 
the rate of 2 per thousand. Nicotine-soap acts rapidly through the 
mouth and quite as rapidly through the spiracles. A lime and copper 
sulphate mixture rapidly liberates the nicotine from nicotine sulphate 
and therefore can produce the full effect of nicotine soft-soap only 
under favorable conditions. The practical conclusion is that tobacco 
extracts should contain as little free nicotine as possible, and that 
they should be used with the stated amount of soft soap. 
