-88* - 
destroyed. Then used with spreaders no ears were protected and no larvae 
killed. Barber also reported on tests on insecticides against the corn 
earworm at Homestead, Fla., from February to April 1937. Soybean oil and 
derris (100 cc. of oil plus 1 level teaspoonful of derris powder), injec- 
ted into the corn ears with a needle nozzle according to the procedure 
described in United States Department of Agriculture ET-92, v/as slightly 
more effective than oil alone. Soybean oil plus solid derris extract was 
applied to corn ears with a needle nozzle. The percentage of ears infested 
was 12, as compared with 45.8 in the check and 8 for ears treated with soy- 
bean oil plus phenothiazine. Soybean oil plus solid derris extract, ap- 
plied with an oil can, gave perfect control. IThen used alone and applied 
with 'a needle nozzle, soybean oil gave the poorest control (56 percent of 
ears infested) of any of the 5 oils tested. Nujol plus solid derris extract, 
applied by means of an oil can, destroyed 100 percent of the larvae; Nujol 
alone permitted 8 percent of the ears to become infested. In all cases 1 
level teaspoonful of solid derris extract (resinate) was added to 100 cc. 
of oil. Barber also reported tests made in Dade County, Fla., during 
February and March 1939 with insecticides for the control of the corn ear- 
worm in sweet corn. Derris extract plus mineral oil; derris extract plus 
cottonseed oil; and rotenone in pine oil, derris powder, timbo powder, and 
Foliafume were tested; also pyrethrins plus rotenone plus cuprous cyanide. 
Oil containing rotenone was not effective, nor was Foliafume. Pyrethrins 
in oil were effective. 
Brannon (46) in 1936 reported that no significant control of the corn 
earworm on lima beans on the Eastern Shore of Virginia v/as obtained with 
derris-talc dusts containing 0.75 or 1.0 percent of rotenone, and that 
sprays of powdered derris and cube roots containing 0.025 percent of rote- 
none gave even poorer control. 
Essig and Michelbacher ( 112 ) in 1936 reported on tomato insects of 
Cal ifornia. In order to avoid the deposit of a residue, a few growers had 
used a derris dust for the control of Heliothis armigera. In places it 
was the only material applied; in others it followed an application of an 
arsenical or fluosilicate dust. The authors stated: "IVhere used alone, 
vre were unable to detect any worthwhile protection but, since so few fields 
were dusted and the observations were so limited, we are not in a position 
to judge its effectiveness." 
Fenton ( 129 ) in 1936 called attention to work done by Ronoy at the 
Texas Truck Crop Experiment Station. Successful control was obtained by 
the use of a dust consisting of 15 pounds of pyrethrum A dust; 10 pounds 
of a 5 percent rotenone-bearing powder; and 75 pounds of 99 percent of 
325-mesh conditioned dusting sulfur, applied at the rate of 20 to 25 
pounds to the acre at intervals of a week or 10 days beginning as sodn • 
as the tomato plants wero placed in the field. The important factors 
seem to be early application and complete coverage. 
Hansberry and Richardson ( 183 ) in 1936 reportod the median lethal doso 
of rotenone in mg, per gm. of body weight for corn earworm larvae to 
more than 0.49. 
