" ^9 - 
Fryer ( lUg ) in I935 reported thi.t derris had "been used against the 
Colorado potato "beetle at Til"bury, England, "but that the exaat degree cf 
success vrill not be knovm for another year, 
Derris v/as effective in field demonstrations. — Kevr Jersey Agricul- 
tural Experiment Station ( 296 ) in 1935. 
' Rohin ( 328 ) in 1935 reported good control of the Colorado potato 
"beetle in Trance i''ithin the follov/ing mixture: Derris povrder (rotenone h 
percent!^ IS percent; pyrethrum pov/der (pyrethrins 0,6 percent), 25 per- 
cent; and clay 57 percent. Excellent results against larvae and adults 
were obtained '.^rhen dusted at the rate of not more than I5 kg. per hectare. 
In discussing insecticides suitable for combating the Colorado potato 
beetle in 193^ (23) , Feytaud stated that powders containing 5 percent of 
cube or' derris were in use for this purpose. 
Eenton ( 127 ) in 193^ referred to an unpublished report of the Texas 
Agricultural S:cperiment Station, v/hich described tests for the control of 
the Colorado pots'to beetle. When 10 pounds of derris (0,5 percent of 
'rotenone), I5 pounds of pyrethrum Pov^co "A" dust (0.75 percent of pyrethrins] 
and 75 pounds of 325-inesh sulfur v/ere employed, all insects were killed 
vrithin 36 hours; vihen 10 pounds of derris (0,5 percent of rotenone)and 
90 pounds of 325-mesh sulfur were employed, 95 percent of the insects 
were killed within ^S hours; and when 25 pounds of pyrethrijjn Povrco "A" 
dust (0.125 percent of pyrt5thrins) and 75 pounds 325-mesh sulfur were 
employed, all insects were killed vithin Us hours, 
Feytaud (129) in I936 recommended rotenone powders for combating the 
Colorado potato beetle. The derris or cube should contain 5 percent of 
rotenone and should be diluted with talc or kaolin. The proportion of 
root powder should be 5 to 20 percent. 
Herman and Hockey of Ilova Scotia ( I85 ) in I93S reported practically 
complete control of potato beetles by the application of Cubor 75 dust 
(0.75' ps^cent of rotenone) or derris-gypsum dust (O.U percent of rotenone). 
Chevalier (S^) in 1937 discussed the use of rotenone-boaring roots 
in France to combat the Colorado potato beetle and other insects. Derris- 
gynsum dusts in laboratory tests gave results as follows^ 
Insect Stage Rotenone dontent Mortality in k days. 
Percent Percent 
Adults 0.5 100 
Adults 0.2 SO 
Adults . 0.1 100 
Larvae ' 1.0 100 
Larvae 0.2 100 
In the field a dust containing 5 percent of derris (equivalent to (3.2 
percent of rotenone) was very effective. — Kelsall and Stultz (2U5) in 1937. 
