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Badertscher and T'other spoon (19) in 1935 compared the stability of 
treated and untreated derris and pyre thrum powders in tests made on the 
larvae of the diamondback moth. Exposure to a light from a Uviarc Iler- 
.cury vapor lamp operating on 118 volts with a current of 4.8 amperes and 
450 watts for 24 hours destroyed about half the toxicity of a derris pow- 
der containing 6 percent of rotenone and 18 percent of acetone extrac- 
tives. Treated powders (treatment not described) prolonged the life of 
these powders v/hen exposed to light. The authors concluded: 
That derris powder requires at least twice as long as pyrethrum 
to lose most of its toxicity when exposed to the action of air and 
sunlight in the summer time. 
That the rapidity of the loss of toxicity in pyrethrum powder 
and in derris powder is largely directly dependent upon the inten- 
sity and duration of the light. 
That derris powder loses its toxicity relatively much slower 
than pyrethrum powder when exposed to air in the absence of direct 
light. 
That treated derris powder after exposure to light and air 
shows. an efficiency from 34 to 93 percent greater than untreated 
derris powder similarly exposed. 
The United States Department of Agriculture, Bureau of Entomology 
and Plant Quarantine (437) reported that at the 1934 meeting of the Amer- 
ican Association of Economic Entomologists Cory led a discussion of field 
results with arsenical substitutes for the control of vegetable insects. 
Roney and Thomas, of Texas, reported that derris-sulfur dust (0.5 percent 
rotenone) controlled this species. W. H« YJhito reported that derris and 
calcium arsenate were approximately equal in effectiveness in controlling 
the larvae of this moth, whereas pyrethrum, cryolite, and paris green 
were comparatively less effective. In general, dusts gave better results 
than sprays. Walker and Anderson, of the Virginia Truck Experiment. Sta- 
tion, reported that it was necessary to use 40 to 50 pounds per acre of 
a derris dust containing 0.75 percent of rotenone in order to control a 
heavy infestation of larvae on heading broccoli. The -Bureau ( 441 ). in 
1935 reported that field-plot tests on cabbage have shown definitely that 
derris-dust mixtures containing from 0.5 to 1 percent of rotenone- were 
effective against the common cabbage worm, less effective against. the 
cabbage looper, and still less effective against the diamondback moth. 
The indications, nevertheless, are that derris powder will be a useful 
material in the control of all three species. In general, pyrethrum-dust 
mixtures were less effective than those of derris against all three. The 
Bureau (442) in 1936 reported that on cabbage, derris and calcium arsen- 
ate were approximately equal in effectiveness in controlling the larvae 
of this species and were more effective than pyrethrum, cryolite, or 
paris green. Experiments in California demonstrated that dust mixtures 
of derris, cube, or pyrethrum gave satisfactory results in the control 
of the three more. common species of cabbage worms on cauliflower. In 
laboratory tests the ground root of devil' s-shoestrings, a domestic pro- 
duct, was found to be as effective against the common species of cabbage 
worms as derris or cubo containing equal percentages of active ingredients. 
