■- ^4 - 
it appeared that the dust mixture containing 1.5 percent rotenone was so 
nearly equal to the mixture containing 2 percent rotenone that the former 
dilution is preferable because of its lower cost. The cube dust Mixture 
proved more effective than a mixture of 50 percent cryolite and 50 percent 
kaolin, or a mixture composed of 8 percent paris green, 42 percent load ar- 
senate, and 50 percent kaolin. Results indicated that there was very little 
difference in the relative toxicity to flea beetles on tobacco plant beds 
between the two last-mentioned dust mixtures. 
Hutscn (209) in 1336 published directions for the control of insects 
with dcrris and pyrethrum. Hutson states "The tern Derris is used for con- 
venience. Present information indicates that cube of equivalent rotenone 
content' is just as satisfactory," 
Laake (256), of the Dallas, Tex., station of the Bureau of Entomol- 
ogy and Plant Quarantine, Division of Insects Affecting Men. and Animals, in 
1935 reported that powdered cubo r^ot, rotenone concentrate, and many other 
materials were ineffective as repellents for stable flies and horn flies 4 
Edwards (124) in 1935 recommended derris or cube dust containing 0.5 
percent rotenone for the control of spittle bugs, A phrophora pemutata Uhl. 
and P hilaenus spunarius ( L cucc phthalnus ) L. , on strawberries in Oregon. 
About 150 pounds of dust per acre are needed to secure control. 
Ewing (133) in 1936 reported that in cage toxicity tests against 
the cotton flea hopper, Psalius seriatus Reut, at Port Lavaca, Tex., a mix- 
ture of 10 parts pyrethrun, 3L0 parts cube, and £0 parts sulphur killed. 15 
percent of the adults and 67 percent of the nymphs. Best control of adults 
(82 percent) was obtained by sulphur-par i s green, 90.: 1C, and best control 
of nymphs (93.5 percent) was obtained with sulphur-pyre thrum, 60:40. 
Smith and Scales (382) reported the following results of cage tests 
made at Tallulah, La., during 1936: 
Control (percent) 
Tarnished 
Treatment Loaf worm pla nt bug 3oll weevil 
Nymph Ad.ul t 
Cube 40$, sulphur 60 fo, 72 54 49 45 
(rotenone 1.96$) 
Cube 20$, sulphur 80$, 58 — 33 28 
(rotenone 0.98$) 
Cube 10$, sulphur 90fo, 31 — 12 5 
(rotenone 0.49$) 
Cube 10$, pyre thru; 10$, 63 71 21 9 
(sulphur 80$ (rotenone 0.49$) 
Cube (rotenone 4.9$) 76 ' 2 50 80 
