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satisfactory results as the c-ther carriers. The addition of 5 perce: [ 
weight of finely ground dusting sulfur seemed to improve the effec ss 
of a derris-talc dust. Based on rctenone content, a cube dust did net 
seem to give so satisfactory control cf cabbage worms as did a derris dust. 
In 1936 these authors ( 461 ) reported tests made in 1932-33 for the control 
of cabbage worms. They concluded that repeated applications cf derris and 
cube dusts containing from 0,5 to 0.75 percent of rotencne and from 2 to 3 
percent of total extractives, and pyre thrum ducts containing from 0.3 to 
0.5 percent, of pyrethrins gave good control, whereas weaker concentrations 
of rotenone and pyrethrins were less effective. Derris and cube dusts 
having approximately the same rotenone and total-ether-extractive • 
appeared to be about equally effective. Derris dusts (0.75 percent rote- 
none) gave 65 percent control of the larvae of the diamondback moth. 
These results indicated that the imported cabbage worm is as susceptible 
to derris as the cabbage looper and the larva of the diamondback moth, if 
not more so. Walker and Anderson (468) in 1937 reported that r ed 
applications of derris and cube dusts containing from 0,5 to 0.75 percent 
of rotenone and from 2 to 3 percent of total extractives at 7- tc 10- 
intervals gave good control of the larvae of the diamondback roth, in 
1937 they reported that a derris pcr.'der supposed to contain 5 percent of 
rotenone actually contained 2.19 percent and 9.32 percent of extractives. 
This test indicated that the nearly full-grown larvae are resistant to 
derris dust but the newly hatched larvae are susceptible, and that repeated 
applications of derris dust containing 0.33 percent of rotencne at the rate 
of 35 pounds per acre at 7 to 10-day intervals will kill the young worms 
as they hatch, resulting in good control. The resistance cf the near] 
full-grown larvae probably accounts for the poor control obtained i r- 
ris in 1934, as a large percentage of the larvae were nearly full grown at 
the time the dusting was done. Kale plants infested with newly hatched 
larvae of the diamondback moth were dusted on October 31 and November 10 
at the rate of about 25 pounds per acre "with derrir.-talc and cu" c --talc 
dusts containing 0,5 percent of rotenone, both in combination wit 
without Are sket. The derris-talc, derris-Aresket-talc . 
dusts gave 82 percent control and the cub e-Aresket- talc i i ave 87 per- 
cent control, indicated very little difference between the effects of any 
of the dusts and that either a derris-talc or a cube-talc dust 
approximately 0.5 percent of rotenone and 2 percent of total extrac tiv 
if applied when the larvae are young, will give a satisfactory control. . 
White ( 480 , 481 ) in 1935 recommended derris dust (0#5 to 1 percent 
rotenone) and derris spray (0.02 to 0.025 percent rotenone) for 
trol of the larvae. He also sumnarized the results obtained 
of Entomology and Plant Quarantine at Chadbourn, .'..." , S. ".. 
Baton Rouge.. La., and Columbus, Ohio, with nonarsenical insec ti- 
the control of the four species of cabbage worms, including the 
back moth: 
Based on the comparative efficiency, at - ical str 
of each of the insecticides tested against each of th< 
species of cabbage worms present, the at 
derris and calcium arse'nate wero approximately equal in effective- 
ness in controlling the larvae of the diamondback . while 
pyrethrum, cryolite, and paris green wore comparatively loss effec- 
tive for control of this species. 
