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Pieris brassicae (L. ) 
Fryer, Stenton, ?attersfield, and Roach ( 149 ) in 1923 reported that 
extracts of Derris elliptica had been shown to have high insecticidal 
value, particularly for caterpillars. The dry root itself may be used, 
finely powdered and worked up with water and soap, or other emulsifying 
reagent. As the pure poisons found in derris root are solids and only 
slightly soluble in water, their toxicity appears to depend upon the degree 
cf dispersion. A biological method of determining insecticidal properties 
qunatitatively is described. It depends on dipping insects, for a con- 
stant period of time (10 seconds), in known strengths of highly dispersed 
suspensoids in dilute aqueous solutions of saponin. The results obtained 
agreed Yvith those given by the chemical method already described. To 
caterpillars of this insect rotenone and derrid (derris resins) are of the 
same order of toxicity as nicotine. 
Van der Laan (244) in 1936 reported that this species is sensitive to 
derris. 
Thalenhorst ( 406 ) in 1937 reported' tests of proprietary derris, py- 
rethrum, and nicotine dusts. Derris gave the best results. 
Etablissements Rotenia, in a letter to R. C. Roark in 1938, stated 
that this pest on cauliflower was killed by a product containing 12 percent 
of powdered Lonchocarpus nicou root (6 percent rotenone content) and 88 
percent of talcum, 
Pieris protodico B. & L, , the southern' cabbage worm 
A derris-dust mixture (20 parts derris of 5-percent- rotenone content, 
40 parts of tobacco dust, and 40 parts of 300-mesh dusting sulfur) is very 
effective in controlling the southern cabbage worm. — Allen ( 11 ) in 1934. 
Haude in advertising literature published by John Powell and Co., New 
York, N. Y., in 1939 recommended cube or 'derris dust (0.5 percent rotenone). 
Pieris rapae (L. ), the imported cabbage worm 
See Colorado Agricultural Experiment Station (73, 74, and 76) on pp. 
76-77 United States Department of Agriculture, Bureau oT^EntomoTogy and 
Plant Quarantine (437) on p. 69 , Crosby et al . (_87) on p. 79 , Hervey 
and Palm (190 ) on p. "*71 , Huckett ( 201 ) on p. 71 , Ohio Agricultural 
Experiment Station ( 314 ) on p. 74 , Roney and Thomas ( 558 ) on p. 76 , and 
White ( 478 ) on p. 67 , under Auto^rapha brasc.icae (Filey). 
A spray of 2.5 pounds of derris plus 3 pints of Sunoco oil (as 
spreader) per 100 imperial gallons of water gave a mortality of over 90 
percent of imported cabbage worms on cabbar^. Dusts of hydrated lime and 
derris were not so effective. The authors concluded that the moistur 
usually retained by cabbage foliage undoubtedly assisted in bringing out 
the toxic properties of derris. Theso tests were mud* in 1924 and 1925 
and were reported by Kelsall et al. (233) in 1G26. 
