61 



of oil. and two of t\\o heavier of these grades were used in the suc- 

 ceeding experiuients. One of thes(> Avas called "creosote oil," and was 

 a rather light oil of a specific gravdty of 1.035 at 00" F., and the other^ 

 bearing no name, was somewhat heavier. The experiments were nec- 

 essarily on a somewhat small scale. Eighty nearly fidl-grown larvae 

 of Culex Htirnulan'< an.d C. jx'i'tnrJmu^i were placed in H (puirts of water 

 and one-fourth ounce of creosote oil was poured in at 1.15 p. m. At 

 5.15 17 pupa? and 8 larva^ were left alive. The next morning at 9 

 o'clock it was found that 8 adults had issued over night, hut all had 

 been killed by the creosote. At 8 p. m. of the same day, twenty-three 

 hours after the introduction of the insecticide, all larva? and pupse were 

 dead. With the slightly heavier oil, 150 larvte 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 1.15 p. m. At 5.15 all were 

 dead except 28 pupae and about 30 larvfe. 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 1.30 p. m. of the same day all 

 the larva^ were dead, but 10 pupae were still actiA^e. On the following 

 morning, at 9 o'clock, forty-two hours after the application, all larvae 

 were dead and the adults had issued from the remaining pupae, 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 pupa? of the same Oulices were placed in 8 quarts of water 

 and one-fourth ounce of creosote oil was added. Twenty hours later 

 many of the pupae were still living, but thirty -six hours from the time 

 of application all Avere 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 larA^ae, 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 1.15 the creosote was 

 poured in jars 1 and 2, no pupas were observed, but all larA^JB were 

 full grown or nearly so. After fifteen minutes 10 pupae were observed 

 in jar 2 and 5 in jar 1. Ten minutes later 15 were counted in jar 2 

 and 13 in jar 1. Twenty minutes later there were 19 in jar 2 and 2i5 

 in jar 1, 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 ha\ang 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- 

 grown larvw struggled violently on perceiving the uncomfortable 

 presence of the creosote, and. as they were just ready to transform this 



