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Empoasca mal i gn a (Walsh), apple 1 erf hopper 
Metcalf and Flint ( 198 ) in 1938 summarized current information on 
derris. Derris sprays are effective in killing the ;/oung nymphs of apple 
leafhoppers. 
The Idaho Agricultural 'Experiment Station (159) in its annual 
report for 1°32 stated that E* mal i gna is an important pest of the apple 
in southwestern Idaho, Among the materials tested and found satisfac- 
tory was Cubor (pyrethrum and rotenone). 
Erythroneura pal lidi Irons (Edw. ), glasshouse leafhopper 
Wilson ( 510 ) in 1938 reported that eradication of the glasshouse 
leafhopper from heavily infested greenhouses is difficult. It is not 
controlled by repeated fumigation with nicotine or with hydrocyanic acid 
gas at concentrations suitable for houses of mixed plants, and both adults 
and nymphs are very resistant to sprays, The best control is obtained by 
ducting rath nicotine, but the dust renders the foliage unsightly for 
some time. Sprays containing derris, pyrethrum extract, or eucalyptus 
oil are much less effective. 
Erythr oneu ra comes auct., net Say, grape leafhoppers 
Ever (97) in 1927 reported that Derrisol at the rate of 1 pint per 
100 gallons killed 100 percent of the nymphs of the grape leafhopper, 
( Typhi ocyba ) Erythroneura comes. Combined with bordeaux mixture 8-8-100, 
it killed 98 percent of the nymphs . Foliage caged 5 days after spraying 
with Derrisol, 1 pint to 100 gallons, indicated approximate control of 98 
percent, and the same combined rath an 8-8-100 bordeaux gave a control 
of 96. percent. As an ovicide Derrisol was not so effective as pyrethrum- 
s o ap emu 1 s i o n , 
Runner, at the 1930 Codling Eoth Conference of the United States 
Department of Agricu.lture (276), reported a commercial derris extract 
at 1:800 to be effective against grape leafhopper nymphs but not against 
the eggs, 
A suspension of rotenone in raiter at 1:100,000 killed 100 percent. H 
Davidson (Qz) in 19 30. 
Used as a test insect ''oy Davidson and Jones (65) in 1931 in study- 
ing the loss of toxicity suffered by rotenone in certain solvents and in 
aqueous suspension. In the field a suspension of rotenone in water 
1:100,000 killed 94,2 percent of grape leafhopper nymphs. 
Currie (59) in 1934 reported that in the Fresno, Calif., area 
a. rctencne-sulfur oust v.as compered, with a nicotine dust against the 
grape leafhopper. One pound of rotenone [derris] vjas mixed rath 8, 10, 
or 12 pounds of sulfur. The dusts -./ere applied at the rate of 20 poinds 
rer acre rath a hand duster during very ~ indy v:eather. At first the 
nicotine mixture showed the quickest and best results, but later there 
