498 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
serving the results of others, that the entomologist had gone about as 
far as possible with the problem of carriers for nicotine dust. It was 
necessary for the chemist to investigate the nature of the reactions 
between the nicotine solutions and the different carriers. Experimental 
evidence indicated that nicotine dust was more effective when made up 
with certain carriers than with others, but the exact reasons were not 
well understood. As a result of the excellent work recently done by the 
economic workers of New York and New Jersey, we now know which 
carriers are active; i. e. (1) those which actually cause the nicotine to 
be released quickly; (2) those which are inactive and have no effect 
on the nicotine, except to expose it for evaporation, and (3) those which 
adsorb the nicotine and retard its release. It was also demonstrated 
that there is a difference in the reaction of nicotine sulphate and Nee 
nicotine to some of the carriers, and that the moisture content of the 
carriers affects dust made from the two types of nicotine differently. 
The entomologist can now proceed to find out whether a very quick 
release of the nicotine or a more gradual release gives the best killing, 
and whethe 1 ' free nicotine or nicotine sulphate makes the most effective 
dust. Probably these will differ in killing power when applied to 
different forms of insects under varying conditions. 
The problem is further complicated from the manufacturer’s view¬ 
point, who does not wish to make a dust which may lose its nicotine 
if held in storage for several months, nor a dust which retains the nicotine 
after the material has been applied. The ideal carrier would be one 
which retains the nicotine indefinitely in storage, but releases it readily 
when the dust is applied to plants. Perhaps the chemist may find some 
material, or combinations of material, suitable for such a carrier. 
Nicotine dust was first manufactured by a cooperative walnut 
growers’ association in 1918 at Santa Barbara, Cal. It proves so 
successful that a subsidiary company of the California Walnut Growers’ 
Association was formed to make dust not only for its own growers, 
but for growers of fruit and vegetables as well. Since then the pro¬ 
duction has increased until there are at least five manufacturers of 
nicotine dust in the western, and six in the eastern United States. 
The total production of nicotine dust is shown as follows: 
Table I. Total Production of Nicotine Dust in the United States 
Year 1919 1920 1921 1922 1923 
Number of factories. 1 2 3 8 11 
Tons produced. 400 225 425 970 1925* 
*Production from one factory estimated for 1921, 1922 and 1923. 
