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of oil, and two of the heavier of these grades were used in the suc- 
ceeding experiments. One of these was called ‘* creosote oil,” and was 
a rather light oil of a specific gravity of 1.035 at 60° F., and the other, 
bearing no name, was somewhat heavier. The experiments were nec- 
essarily on a somewhat small scale. Eighty nearly full-grown larvee 
of Culex stimulans and C. perturbans were placed in 3 quarts of water 
and one-fourth ounce of creosote oil was poured in at 4.15 p.m. At 
5.45 17 pup and 3 larve were left alive. The next morning at 9 
o'clock it was found that 8 adults had issued over night, but all had 
been killed by the creosote. At 3 p.m. of the same day, twenty-three 
hours after the introduction of the insecticide, all larvee and pupze were 
dead. With the slightly heavier oil, 150 larve of the same species, 
all full grown or nearly so, were placed in 2 quarts of water and three- 
sixteenths ounce of the oil was added at 4.15 p.m. At 5.45 all were 
dead except 28 pupe and about 30 larve. The next morning at 9 
o’clock it was discovered that 10 adults had issued over night, but had 
been killed before flight by the oil. At 4.30 p. m. of the same day all 
the larvee were dead, but 10 pupee were still active. On the following 
morning, at 9 o’clock, forty-two hours after the application, all larvee 
were dead and the adults had issued from the remaining pupe, but 
had been caught by the oily film in the act of issuing and had died 
upon the surface of the water. 
Still another experiment was tried with pupae only. Two hundred 
and fifty pups of the same Culices were placed in 3 quarts of water 
and one-fourth ounce of creosote oil was added. Twenty hours later 
many of the pupe were still living, but thirty-six hours from the time 
of application all were dead, no adults having issued. A check experi- 
ment with kerosene was carried on parallel with this last experiment 
with creosote, and it was noticed that the action of the kerosene upon 
the pupae was much quicker, all dying within forty-five minutes. A 
few young larve, however, in the same jar lived for several hours. 
An interesting effect of the application of the creosote in the first 
two of these experiments was that it seemed without doubt to hasten 
the transformation of the. insect. When at 4.15 the creosote was 
poured in jars 1 and 2, no pup were observed, but all larve were 
full grown or nearly so. After fifteen minutes 10 pupze were observed 
in jar 2and 5 in jar 1. Ten minutes later 15 were counted in jar 2 
and 13injar1. Twenty minutes later there were 19 in jar 2 and 2% 
in jar1. Fifteen minutes later still there were 19 in jar 2 and 22 in 
jar 1. Thirty minutes later there were 17 in jar 2 (2 having died in 
the interval) and 28 in jar 1. As above stated, over night a number 
of adults issued, 10 in jar 1 and 8 in jar 2, and twenty-four hours later 
10 more adults issued in jar 1. It must be remarked that the full- 
erown larve struggled violently on perceiving the uncomfortable 
presence of the creosote, and as they were just ready to transform this 
