Host plant 
- 62 - 
Str ength of dus t in g, mixture 
Rote none : Ether extract 
Green aphid s: 
Rose ------ 
Do 
Do - - 
Plum 
Black aph ids; 
Garden beans - - 
Cherry - - - - - 
Poppy - 
Dahlia - - - 
Percent 
1.50 
1.00 
.50 
.50 
1.00 
.50 
.50 
Percent 
0.6 
1.2 
2.4 
1.2 
1.2 
2.4 
1.2 
1.2 
Mortality 
Percent 
59 
74 
89 

70 
67 
5 
2 
The authors concluded that satisfactory results "by dusting with. 
derris powder against aphids can be expected in only a few cases. Spray- 
ing with derris extracts is to be favored. 
Van der Laan (177) in 1935 reported dihjrdro rotenone to be less 
toxic than rotenone to red and groen aphids. 
Miles and Miles ( 200 ) in 1935 discussed insect pests of glasshouse 
crops. They stated that aphids can be destroyed with 1 pound of derris 
powder per 100 imperial gallons of water, and about 6 gallons per 50 
square yards of crop should be applied as a drench. 
The New Jersey Agricultural Experiment Station ( 206 ) in 1935 
reported that derris and cube are practically equal in their toxicity to 
aphids, provided they contain about the same amounts of rotenone and total 
extractives. 
The Rubber Service Laboratories Company, Inc. (238) (a subsidiary 
of Monsanto Chemical Company), in 1935 recommended a mixture of 7 parts 
of derris resin, 33 parts of dry Areskap, and 60 parts of either pine 
oil or oleic acid at 1:800 for aphids. 
Van der Scheer (239) in 1935 reported that rotenone-benzene omulsi 
(1 gm. rotenone, 20 cc. benzene, and 30 cc. avater containing 0,1 to 0,15 
gm. Igopon T) at a concentration of 1:5,000 gave good control of the gre 
aphid. 
The Deli Experiment Station, as reported by the Koloniaal Institui 
of Amsterdam. (1_74, 175) in 1936, I ound undiluted ground T ephrosia toxica ] 
root to have slight effect on leaf aphids, but derris was much more 
effective. 
1936. 
Aphids in general are sensitive to derris. — Van der Laan (178) in 
Van der Vecht (287) in 1936 wrote that for the control of Aphidids 
[=Aphiidae] spraying with rotenone suspensions containing 0.005 to 0,02 
percent of rotenone can be recomm ended, /.doing a spreader improves the 
effectiveness of the spray. 
