-21- 
dihydrodeguelin > rotenone > active isorotenone (= inactive 
d ihydrorotenone) > deguelin > inactive isorotenone. Comparisons 
were m-:de by plotting concentration (rag. oer liter) against 
the reciprocal of the mean time (minutes) to kill 50 percent 
of the larvae. The authors "believed that the toxicity of der- 
ris extractives can be attributed pertly to the optically active 
deguelin known to be present. 
^oke ( 324 ) in 1938 showed that the toxicity of finely 
powdered rotenone to mosquito larvae is not altered to a demon- 
strable extent after 18 hours of incubation in the dark at 29° G. 
with the/'contents of the digestive tract of the southern armywDrm. 
/•various tissues or "with the 
Phillips and Swingle ( 234 ) in 1940 reported on the rearing 
of mosouito larvae of Culex ouinquefascietus Say at Sanford, Fla. , 
and the effect of diet on their resistance to rotenone and 
nicotine. The percentage of kill after 18 hours by rotenone at 
5 p. p. m. ranged from 15 to 91 percent, according to the diet. 
Of larvae collected in the field, 72 percent were killed by 5 
p. p. m. of rotenone and 78 percent by 100 -p. p. m. of nicotine. 
Culex territans ^elk. 
See Campbell et al. (56) under Culex pipiens L. on -page 17. 
Culex sp. 
Campbell (50) in 1932 published a critical review of the 
recently published literature on the insecticidel value of 
rotenone and of much unpublished data obtained by Federal and 
Stete entomologists. The action of rotenone on Culex sp. as 
determined by Davidson (67) in 1930 and by Sheperd ( 249 ) in 1931 
was reviewed. 
Corbett, entomologist for the Federated Malay States Depart- 
ment of Agriculture (82) in 1934 reported that the effect of derris 
solutions on larvae of Calex sp . was tried, and. comparative tests 
with nicotine sulfate were also carried out. 
Miller ( 204 ) in 1935 described tests on various insects, 
including Culex larvae, for the evaluation of different species 
of Derris . Larvae of Culex sp. in 500 cc. of water were treated 
with 1 cc. of an aaueous solution of D. elliptice at a concen- 
tration of 1 kg. of root to 25 liters of ^ater, and 94 oercent 
of them were dead after 4 days. 
Stegomyia so . 
Worsley ( 326 ) in 1934 reported that tests on mosquito larvae 
(10 in each test) of this species yielded the following results: 
