August, ’23] CONNOR & MONROE: KILLING STEGOMYIA LARVAE 
383 
in the bottles from which air had been excluded mechanically. Salad 
oil must, therefore, lack the toxic properties of petroleum. 
There is a vast difference in the behavior of larvae whose air supply 
has been excluded by mechanical means and that of the larvae which 
have been deprived of air by a film of kerosene. The former seek to 
retain their position at the surface of the water, thrusting their syphons 
again and again against the cover glass and continuing a rapid movement 
up and down until they die from utter exhaustion. Under a film of 
kerosene, on the other hand, the larvae will either almost immediately 
leave the surface, dropping down to the bottom of the container where 
they remain prone for long periods of inactivity followed by spasmodic 
movements of their posterior abdominal segments, or else they will float 
on the surface of the water wriggling little if at all. 
Table I.—Length of Life of Aedes calopus Larvae in Water Covered with 
Petroleum Film. Periods of Exposure X to lk Hours. 
(Figures indicate the number of surviving larvae) 
Pet. Not Removed 
Petroleum Removed After 
Time 
Bottle 
1 
Bottle 
o 
U hour 
K hour 
1 hour 
1>2 hour 
Bottle 
Bottle 
Bottle 
Bottle 
Z 
3 
4 
5 
6 
(9.40) a. m. 
20 
20 
20 
20 
20 
20 
9.45 
15 
14 
15 
14 
13 
10 
9.50 
12 
11 
13 
12 
11 
8 
10.00 
7 
8 
13 
10 
7 
5 
10.10 
4 
5 
5 
6 
3 
5 
10.25 
3 
3 
4 
3 
3 
2 
10.40 
1 
2 
3 
3 
2 
2 
10.55 
2 
2 
3 
1 
1 
11.35 
1 
1 
1 
12.15 p. m. 
1 
1 
1 
2.00 p. m. 
1 
