444 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
withstand the severe cold. In the second place the weather was unus¬ 
ually severe. Weather records for the past twenty years fail to show 
a similar occurrence. The minimum temperature records for the va¬ 
rious sections are as follows: Clarkston, —26; Walla Walla, —36; 
Yakima, —24; Prosser, —30; Wenatchee, —16 and Spokane, —15. 
Chairman A. L. Melander: Mr. R. K. Vickery will now give a 
paper, “Petroleum Insecticides.” 
PETROLEUM INSECTICIDES 
By Robert K. Vickery, Assistant Entomologist, California Spray-Chemical Co. 
The government lately published a warning foretelling the rapid 
depletion of our petroleum resources. We are now using millions of 
gallons of oil to kill insects. A shortage will inevitably multiply the 
price many times and, if I may, I would like to discuss briefly the 
subject of petroleum insecticides and also incidentally record a few 
observations and experiments. 
In the past it has been economical to use the petroleum products of 
commerce for insecticides. Efficient sprays were made from kerosene, 
crude oil, lubricants, and the by-product distillates. The everyday 
household and industrial demand for these oils made them available 
in every market. Certain products, suitable for insecticides, were 
relatively cheap. Today these oils are sometimes hard to obtain and 
the price has trebled within the last five years. The reason is not hard 
to find. The refiners now find it profitable to make cracked gasoline 
and lubricants out of these cheaper oils. 
With such excellent insecticides at hand there has been little incen¬ 
tive to study the toxicology of petroleum to insects. For many years 
it was presumed that these oils suffocated the insects by mechanically 
closing the spiracles. Shafer and others have shown that petroleum is a 
true chemical poison. This is simply demonstrated by the rapid killing 
of an insect confined in an atmosphere saturated with the gases given 
off by kerosene. Shafer also showed that for all practical purposes 
it was impossible to smother an insect. With the idea of suffocation 
in mind it was easy to select an oil purely by the physical properties, 
specific gravity, viscosity, etc., used to distinguish oils industrially. 
Toxicology is fundamentally a chemical study and little is gained by 
testing the insecticidal values of different oils distinguished from one 
another by their physical properties. We must go deeper and study the 
oils as chemicals if we are to improve our present knowledge. 
