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in water and tested against many kinds of insects, in the laboratory. 
Observations showed that, with, the dosagejs used, the red spider suffered 
only a light mortality. . 
Wilson ( l69 ) in 1931- reported tests with sulfur dusts, nicotine, 
pyrethrum extract, derris extract, soap-and-white-oil emulsions, and 
miscible oils against the two-spotted mite on Asparagus plumosus in Florida. 
White-oil emulsion (1:100), thoroughly applied at 7-day intervals, was the. 
safest and cheapest insecticide. The sulfonated-oil derivative [Penetrol?] 
was used as a spreader. with a compound of derris, but after a few days the 
plants showed severe burning. Sprays in which the derris compound (1:^00) 
was used gave good controls and no burning effects. When the derris- compound 
was used at. a dilution of 1:600, 85 percent of the mites were killed. 
Brooks, Watson, and Mowry (17) in 1932 stated that in Florida dusting 
strawberry plants with-flowers of sulfur is the quickest and most economical 
way of combating red spiders. Nicotine sulfate, pyrethrum, and derris 
compounds are also good insecticides for red spiders. 
■■ Campbell (Uo) in 1932. reviewed work by H. H. Richardson, of the Division 
of Truck Crop and Garden Insect Investigations, Bureau of Entomology and 
Plant Quarantine, United States Department of Agriculture, and others, with 
rotenone as. an acaricide. Richardson proved that wetting and spreading 
agents greatly increased the effectiveness of rotenone suspensions against 
the common red spider on a .kudzu vine in a greenhouse. The experiments were 
carefully controlled and mortality counts were made after- 2^ hours. Rotenone 
at 1:5.000 killed 12 percent of the adult mites; at 1:5.000 + potassium 
oleate (l: U00) , from 5^ to 78 percent. The soap solution alone killed from 
9 to 11 percent, a mortality not much greater than that : in the untreated 
checks. .. The increased -effectiveness of the rotenor?e-soap mixtures was there- 
fore due to rotenone, aided in some checmical or ; physical way by potassium 
oleate. Rotenone at 1:1,000 with potassium oleate (l:U00) killed only 67 
and 83 percent of the mites, a fivefold increase in concentration producing 
very little increase in mortality. W. M. Davidson, of the Food and Drug 
Administration, United ^States Department of Agriculture, killed 6U. 5 percent 
of the mites with rotenone at 1:1,000 without a wetting and spreading agent 
but, since his methods are not described, his result does not necessarily 
contradict those of Richardson. By adding Penetrol to rotenone suspensions, 
Darley killed 75 percent of the mites in 2k hours with rotenone at 1:100,000 
and 90 percent at 1:50,000 — much greater dilutions than those used by 
Richardson. Whether Penetrol increages the effectiveness of rotenone sus- 
pensions more than does potassium- pleate can be determined only by paired 
experiments. Richardson also tested sulfonated castor oil as a wetting and 
spreading agent for rotenone suspensions, and found it less effective than 
potassium oleate. Both Richardson and M. M. Darley, of the Division of 
Cereal and Forage Insect Investigations, found that rotenone with wetting 
and spreading agents was more effective against the common red spider than 
.were the pyrethrins or nicotine with the same agents. 
