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Danneel (65) ljn 1933 reported that 7 hours tes necessary to 
Ccuse loss of motion in mosruito. larvae In solutions of rotenone of 
0.001 percent concentration (10 p. t>. ir..). 
Gnadinger ( 117 ) in 1933 cited unpublished work hy Ginsburg 
which indicates that the -oyrethrins ere more toxic than rotenone 
to mosouitoes. 
Jones et el. ( 156 ) in 1933 reoorted on the loss in toxicity 
to insects of deoosits of rotenone and related materials when 
exoosed to light. Rotenone, dihydrorotenone, rotenone hydro- 
chloride, rotenone-bentonite (1:1), rotenone-lampblack (1:1), 
ground derris root, and powdered derris extract "-ere each made 
into a paste with water and painted heavily on weighed, glass slides. 
After the deposits had dried the slides were weighed again. Or.e 
group of slides was exposed to direct sunlight for 10 days during 
April and May, a second group to sunlight for 20 days, a third 
group to arc light for 240 hours, a fourth group", of the three pure 
compounds only, to arc light for 480 hours, and a fifth group ^as 
kept in the dark at room temperatures. The deposits on these 
•slides m ere tested ageinst culicine mosquito larvae and goldfish 
to determine the percentage loss of toxicity resulting from 
exposure to light. In all cases the exposed deposits were decidedly 
less toxic than the unexposed and, with one exception, the loss of 
toxicity increased vith increasing exposure. Rotenone, rotenone- 
bentonite, derris root, derris extract, and rotenone hydrochloride 
lost more than half of their toxicity during 10 days' exoosure to 
sunlight. Their toxicity was practically destroyed by the exposure 
to arc light. Since dihydrorotenone lost only One-fourth to one- 
third of its toxicity during- the first 10 days' exposure to sunlight 
it was distinctly more resistant to detoxication during this period 
than rotenone. At the end of 20 days in sunlight, however, and afte: 
exoosure to arc light, it had lost toxicity to about the same extent 
as rotenone - . Lampblack markedly reduced the loss of toxicity of 
rotenone during .the first 10 days' exposure to sunlight and pre- 
vented further loss during the last 10 days. It also -rave some pro- 
tection to rotenone under arc light. Neither bentonite nor the 
substances' Occurring ^ith rotenone in powered derris root and derrii 
extract protected rotenone from loss of toxicity. The unexposed 
powdered derris extract containing about 25 percent of rotenone "»as 
as toxic to mosouito .larvae as pure rotenone. It -as sho^n thrt the 
photochemical decomposition of -dry rotenone, which results in loss 
of its toxicity to insects and fish, does not take piece in the 
absence of oxygen. . 
Spoon ( 257 ) in 1933 reported tests of rotenone as en insecticidi 
in Holland and stated that rotenone appeared to have no value agains' 
full-grown mosauitoes. 
Turner ( 278 ) in 1933 recorded tests of insecticides against 
mosquito larvae in Connecticut. Preliminary tests made in 1931 
showed that the use of rotenone with fuel oil ""as not so effective 
