334 
MALARIA 
performs definite functions. In order to 
either prepare or select a toxic mosquito oil 
it is important first to ascertain the proper¬ 
ties responsible for toxicity. Various the¬ 
ories have been suggested to explain how 
petroleum oil kills larvae, among which the 
following deserve reviewing. 
1. Suffocation. (A) The layer of oil on 
the surface of the water prevents the larvae 
and pupae from obtaining air (Celli 1900; 
Hardenburg 1922). (B) Oil impairs respi¬ 
ration of larvae by entering the tracheae 
effectually blocking them (Green 1924). 
2. Toxicity of Oil Vapors. Toxic vapors 
from the inspired oil penetrate the tracheal 
tissue and produce a lethal effect upon 
larvae (Shaffer 1911; Takatsuki 1917; Mc- 
Fie 1917; Freeborn and Atstat 1918; Green 
1924; Ramsay and Carpenter 1932). 
3. Narcotic Effect. The toxic vapors 
from the inspired oil do not kill larvae 
directly but act as a narcotic, paralyzing 
TABLE I 
Summary op Laboratory Tests With Different 
Petroleum Oil Fractions on Larvae of 
Culex Pipiens and Aedes Vexans 
(Copied from Ginsburg 1929) 
Petroleum 
oil tested 
Boiling 
range 
degrees F 
Viscosity S.U. (a) 
100° F 
Per cent volatility 
in 48 hrs. at 80° F 
Approximate gal¬ 
lons of oil applied 
per acre 
Time to kill 100% 
larvae 
Fraction 1 
200-300 
25 
100 
24 
30 m 
“ 2 
300-400 
28 
94 
24 
15“ 
“ 3 
400-500 
31 
83 
24 
15“ 
“ 4 
500-600 
40 
24 
24 
1 h 
“ 5 
600-650 
12 
24 
3“ 
“ 6 
650-750 
182 
5 
24 
14“ 
Mosquito 
oil . 
320-755 
50 
50 
24 
30 m 
Fuel oil M 
360-725 
36 
35 
24 
1 h 
Fuel oil S 
430-630 
40 
22 
24 
2 ‘ ‘ 
Light ma¬ 
chine oils 
Straw 
paraffin 
552-765 
65 
10 
24 
18 “ 
“ t < 
552-765 
65 
10 
100 
9 “ 
“ “ 
552-765 
65 
10 
200 
9“ 
Diamond 
paraffin 
638-770 
110 
0 
24 
22“ 
“ “ 
638-770 
110 
0 
100 
12 “ 
the nervous system. They are thus ren¬ 
dered helpless and subsequently drown 
(Barnes 1925). 
Laboratory and field experiments con¬ 
ducted in New Jersey (Ginsburg 1928, 
1929), with different commercial mosquito 
oils and with various fractional petroleum 
distillates indicate that the toxic properties 
are closely related to volatility and boiling 
range. Volatile, low-boiling distillates 
penetrate and kill larvae and pupae quickly, 
whereas oil fractions of high boiling range 
and of low volatility possess little or no 
direct toxicity, causing death primarily by 
suffocation but only after long periods of 
exposure. 
From the results of these investigations 
it appears that petroleum oil films kill mos¬ 
quito larvae by the following method. 
While in the process of breathing on the 
water surface, the larva also draws in oil 
from the surface film into its tracheal sys¬ 
tem by the flaps, in case of Anopheles, and 
by the breathing tube in case of other spe¬ 
cies. After penetration the toxicological 
effect will vary with the type of petroleum 
product used. Oils of low boiling range 
and of high volatility will exert a direct 
toxic action within a very short time. On 
the other hand, high boiling, non-volatile, 
viscous oil will slowly cause death by suffo¬ 
cation, after the tracheal stems have become 
filled with oil. The rate of penetration 
seems to be proportional directly to the 
thickness of the film and inversely to the 
viscosity of the oil. 
The information secured from these ex¬ 
periments have simplified the problem of 
developing specifications for efficient mos¬ 
quito oils. In general, the oil should con¬ 
tain enough of a low boiling petroleum 
fraction to insure quick penetration into 
the tracheal system and rapid kill of larvae 
and pupae; and a sufficient quantity of a 
high-boiling fraction to leave a lasting film. 
An example of such an oil is given in Table 
II. This oil has been effectively used in 
New Jersey during the last few years and 
can be readily obtained from most of the 
oil refineries at a cost varying from 5.5 to 8 
cents per gallon depending on quantity pur- 
