-47- 
Leptinotarsa decemlineata (Say) , the Colorado potato beetle 
A 10-percent yam bean dust killed 100 percent of the larvae 
in less than a day, but sprays containing up to 8 pounds of ground 
yam bean per 100 gallons of water were less effective than 1 pound 
of 5 peroent cube in spray,— Anonymous (7) • 
In laboratory tests, derris, cube, timbo, and Tephrosia Virgini - 
ans, mixed with talc or sulfur to give 0.5 percent of rot en one, were 
very effect ive.~ Arant (22 , 26) . 
In laboratory tests using 10 fourth-instar larvae in each ex- 
periment, records were made of the exact time at which the different 
symptons of the p'oisoning and paralysis of the larvae took place. 
When dusts containing 0.5 percent of rotenone, used as contact poi- 
sons, were compared by this method, derris proved superior to cube, 
and cube to timbo, but preparations of derris, cube, or timbo differ- 
ed among themselves. The toxicity of cube dust wes affected by the 
carrier used with it. The time required for larvae *o become com- 
pletely ppralyzed varied with the temperature. In tests with cube 
dust (6 percent of rotenone) alone, or diluted with talc to contain 
0.9 percent of rotenone, there was no great difference in rate of 
action of the two dusts at any one temperature, but the talc appear- 
ed to exert a desicoating effect that assisted the lethal action of 
the rotenone. High temperatures accelerated the action. The applica- 
tion of rotenone dusts during the warmest part of the day is there- 
fore reoommended. The effectiveness of the cube-talc mixture was 
unaffected by darkness.— De Lapparent (355 ) ; Feytaud and De Lapparent 
(184). 
Tflhen use of arsenicals is undesirable in France, potatoes may 
be dusted with derris or cube, but the cost is higher. The necessity 
of common action is emphasized if the potato beetle is to be con- 
trolled.— Feytaud (182) . 
The best preventive measure in Europe is to spray all potato 
fields with lead or calcium arsenate. In situations where the use 
of arsenicals is dangerous, dusts or sprays of nicotine or rotenone 
should be used.— Mayne (409 ) . 
Rotenone or rotenone plus Bordeaux mixture, is considered good 
for the potato beetle in victory gardens in Indiana.— Reed (496 ) • 
Derris-talc dusts were effective and acted quickly in Germany, 
but derris sprays were not so effective.— Sellke (535) • 
