-48- 
of DDT in 10 ml* of Triton X-100 and sufficient Velsiool AR60 to make 
100 ml.— Ross (306 ). 
Maorosiphum pi si (K2tb«), the pea aphid 
Under greenhouse oonditions at Madison, "Wis., a 10 percent DDT-py- 
rophyllite mixture killed all aphids after 1 day; a 5-peroent mixture 
after 2 days; and a 1-peroent mixture after 3 days. The mortalities 
were much higher at 63 -65°F. than at 51°-55°. In tests conducted on 
the residual effect of DDT "when dusted on pea plants, the residues of 
the 5-percent and 10-peroent dusts applied 1, 3, 5, 11, 14, and 21 
days before exposure to aphids gave 84 percent mortality of the aphids 
in 1 day and 100 percent mortality in 3 days. In other tests the 1 
percent and 0.5 percent strengths of DDT had greater residual effect 
than did mixtures containing 0.5 percent of rotenone. At Columbus, 
Ohio, the aphids were tested by use of a bell-jar duster. DDT was 
very effective and appeared to be more so than derris at comparable 
strengths. A 0.625-percent mixture killed all the aphids 3 days 
after dusting.— Dudley et al. ( JL39 ) • 
Both 5- and 10-percent DDT aerosols applied at 10 pounds of so- 
lution per acre (lj pound of actual DDT) gave 85 to 99 percent re- 
duction of pea aphid populations as compared with untreated plots* 
Ten pounds of aerosol solution oontaining 6 percent eaoh of DDT, cyclo- 
hexanone, and lubricating oil, 35 percent of acetone, and 50 percent 
of methyl chloride per acre has given excellent control of the pea 
aphid.— Ditman (133 ). 
A dust oontaining 3 percent of DDT gave oontrol as good as the 
oommonly used rot enone-1 ethane or rotenone-niootine dusts. However, none 
of these gave entirely satisfactory results and in one instance where 
the results were especially poor, the grower retreated the whole field 
with vaporized nicotine.— Walker (365 , 366 ). 
During August and September in California several mixtures contain- 
ing oil and DDT were applied to peas as vapo-sprays. From the standpoint 
of pea aphid control, DDT appears to be fairly effeotive in oil when 
applied by the vapo-spray machine; the kill is in direct proportion to 
the amount of DDT present. Combinations of 1.2 percent DDT and 0.05 or 
0.25 peroent rotenone were superior to 1.2 percent DDT alone, and about 
the same as 2.4 peroent DDT.— Lange (241) • 
Tests were made on acre plots of Alaska peas. A spray of 1 pound 
of DDT and £ pound of Vatsol OS in 100 gallons of water was compared 
with a spray oontaining 3 pounds of cube powder (5 peroent rotenone) and 
£ pound of Vatsol OS. Sprays were applied at the rate of 180 gallons 
to the acre at 325 pounds' pressure. A 3-perosnt DDT dust was compared 
with a 0.75-peroent rotenone dust, a 2 percent free niootine-0.5 peroent 
