74 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
apparently death was due to only the portions of this fraction with the 
lowest boiling points. From these results it would appear that only 
the lowest fractions of kerosene would be effective when it is used as 
a contact insecticide. 
Toxicity of Kerosene Emulsions to Insects 
"To determine the accuracy of this point different kerosenes and 
their fractions were used in a 5 per cent emulsion as a spray for the 
destruction of the snowball aphis, Aphis viburnicola Gillette. These 
are sprayed with a 5 per cent emulsion of the oils and their fractions. 
The aphids were counted before and after spraying to determine the 
per cent killed. Results of these experiments are shown in Table IV. 
These data show decidedly contrary results to what might be ex¬ 
pected. The higher fractions were in all the oils most toxic. As a check 
snowball aphids were sprayed with a soap solution of the same strength 
as that used in the 5 per cent emulsion with the result that only 30 
per cent of the aphids were killed. The effectiveness of the high boil¬ 
ing point fractions cannot be due to the soap in the emulsion nor can 
it be due to any influence on the penetration of the oils or the lower 
boiling points would also have shown this influence. It would appear, 
therefore, that the death of the insects from high boiling point com¬ 
pounds is not due entirely to the vapor. This matter is being investi¬ 
gated and will be reported later. 
Table IY—Per Cent of Aphids Killed by a 5 Per cent Emulsion 
Oil 
Unfractionated 
First Fraction 
Second Fraction 
Third Fraction 
A 
81.5 
56.5 
94 
90 
B 
74 
66.66 
100 
100 
C 
90 
66.66 
77 
100 
D 
90 
90 
76 
96 
E 
80 
60 
89 
100 
Conclusion 
The results of these experiments point out conclusively the great 
variation in the toxicity of different types of kerosenes to both insects 
and plants. Although an imperfect emulsion would naturally result 
in injury to plants, it by no means follows that where burning does 
occur that it is always due to an imperfect emulsion. The cause of 
the burning may be entirely due to the type of kerosene used. So 
great is the difference between kerosenes that it is quite possible to 
use certain types of kerosene pure upon certain plants under favorable 
climatic conditions. Inasmuch as kerosenes even of the same brand 
