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The cabbage looper is more resistant than Pieris rapae to rotenone 
dust, "/hen it is young a dust containing 0.5 percent of rotenone gives 
satisfactory control but a dust containing 0.75 percent of rotenone should 
probably be used. The applications should be made before the loopers 
become half grown. — Howard and Mason ( 196 ) in 1937. 
Hutson ( 209 ) in 1937 recommended derris dusts or sprays for the cont- 
rol of the cabbage looper. 
Kelsall and Stultz ( 234. ) in 1937 reported that in laboratory tests 
derris-gypsum dusts containing 5 and 12. f percent of derris (4- percent rote- 
none) caused mortalities of 33 and ^0 percent, respectively, in 1 day. 
In the field derris gave fair control, pyrethrum excellent control. 
The Louisiana Agricultural Experiment Station ( 257 ) in 1937 recom- 
mended derris dust (1 percent rotenone) for the c:ntrol of cabbage worms, 
including the cabbage looper. The sane station (258 ) in 1938 published a 
summary of entomological progress, in which C. E. Smith reported that in 
reducing cabbage looper populations derris dust containing 1.0 percent 
of rotenone was superior to all other treatments; derris dust containi- - ^ 
0. c percent of rotenone and synthetic cryolite was next in effectiveness 
and superior to dusts containing 0.1 and 0.0 r percert of pyrethrin I. 
The New York Agricultural Experiment Station ( 3 02 ) in 1937 reported 
that in 1935 infestation by the cabbage -looper increased seriously on 
late-grown cauliflower and cabbage. The larvae were not readily killed 
by applications of roteno v 'e-containin<? sprays or dusts, especially after 
they had attained medium size. Insectary tests showed that the larvae 
could be killed by contact applications of dusts containing pyrethrins. 
This station ( 303 ) in 1938 reported that field trials with derris, cube, 
timbo, and pyrethrum powders for cabbage worm control indicated clearly 
that pyretrrum mixtures were more effective where the cabbage looper was 
the predominant species. Mixtures of comparable strength Containing cube 
and pyrethrum powders were not so ef Pective as those containing' pyrethrum 
powder alone. Spray mixtures were less effective than dust mixtures. 
The New York County Agents' Training School ( 299 ) in 1938 discussed 
the control of vegetable insects. Glasgow, Huckett, liervey, and others 
recommended rotenone dusts and sprays as follows: Rotenone dust con-- 
•taining 1 percent of rotenone proved to be one- of the most effective 
treatments for cabbage looper control. The drawback to its uso is its 
cost, as co par^d with that of lead arsena.-'e. Compared with lead arsenate 
spray, rotenone dust give as good or better immediate kill of both the 
imported cabbage worm ?nd the cabbage looper but the lend arsenate spray 
had a greater residual effect and remained affective longer. The rotenone 
dust gave a better immediate kill and was about equal or better in resid lal 
effect. On Long Island rotenone-containing dusts were also used larerely 
in 1938 as a substitute for pyrethrum dust, and in the absence of serious 
cabbago looper attack they afforded protection. 
The North Central States Entomologists ( 309 ) in 1938 discussed the 
control of certain insects by the use of cube and derris. Compton repor- 
ted that rotenone-bearing dusts or s. rays, and li senate dusts or 
sprays gave the best results. Both these materials were i 'fective against 
