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holic extracts of various species of derris plus soap were effective 
against this aphid. Derris applied as a dust killed 92.3 percent. In 
I92U Mclndoo and Sievers ( 188 ) reported the cold alcoholic extract of 
cube used vrith soap to "be effective. A dust of 2 parts of rotenone and 
98 parts of diatomaceous earth killed 68. ^ percent of these aphids on a 
tuliptree. — Davidson (63) in 1930. 
Macro siphum pisi (Kalt.), the pea aphid 
Cory (53, 5U) reported in 1923 that lime to which 5 percent of 
Derrisine was added, used at the rate of 50 pounds per acre, killed only 
10 percent of ( Illinoia ) Macro siphum pisi . In 193^ he reported that 
rotcrione "Vast was especially efficient in the control of the pea aphid. 
Rockwood and Chamberlin ( 235 ) in May 193^ reported on the action 
of derris dust on the pea aphid at Forest Grove, Oreg. Austrian field 
peas infested by aphids were dusted on April l6 with derris dust contain- 
ing a silica filler, the rotenone content "being 0.5 and 0.7 percent. 
The naximum reduction of aphid? in the best parts of these plots was not 
over 50 percent and nothing approaching practical control was obtained. 
Dudley (oU) , of the Madison, Wis. , laboratory of the Bureau, in 
December 1935 reported insecticide tests against the pea aphid. After 
the pea vines became heavily infested, the application of derris sprays 
containing 0.01^8 percent of rotenone reduced the aphid population ap- 
proximately 95 percent, in comparison with the untreated plots, and re- 
sulted in a profitable yield of peas. Most of the derris sprays were 
applied with commerci-lly prepared sulfonated phenyl phenol (1:600), 
which functioned as a spreader and wetting agent. In comparative tests 
vrith this agent, sodium lauryl sulfate (1:1,500), and sodium oleyl sul- 
fate (1:d00) no significant difference could be determined in the perform- 
ance of the three materials. Derris sprays without spreaders or wetting 
agents caused slower but eventually as good reductions in aphid popula- 
tions as when spreaders a^id wetting agents were used. Derris dust contain- 
ing 0.5 percent of rotenone applied in a heavy infestation gave erratic 
results, inferior to those from the derris sr>rays. 
Bronson (22, 2J, 2U-, 25, 26, 27) in IQ36 reported the results of 
greenhouse tests of derris against the pea anhid made at Madison, Wis. 
Tests in vrhich aphid-infested plants were treated with various dust mix- 
tures, and placed in a chamber where the relative humidity remained at 
approximately 100 percent for a period of l6 hours after treatment gave 
much more effective control than in com-narable tests in which the dusted 
plants were left in an open greenhouse. Derris-dust mixtures containing 
0..U percent of rotenone, with talc as the diluent, plus sodium oleyl sul- 
fate as a conditioner, were more effective in greenhouse experiments than 
were derris-dust mixtures with kaolin or gypsum a* the diluent, plus 
sodium oleyl sulfate as the conditioner, when the plants were left in the 
open. When treated plants were placed in a moist chamber, where the 
•prevailing relative humidity was approximately 100 percent, no significant 
differences could be*detected between the performance of each of the 
three dust mixtures with different diluents. Better results were obtained 
with derris-dust mixtures containing a conditioner (i.e., sodium oleyl 
sulfate special) than with the unconditioned dust3. During the winter of 
