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Derris was Ineffective against the corn earworm. — Hutson ( 208 ^ 209 ) 
in 1936 and 1937. 
E, P. Jones ( 225 ) in 1936 reported that in laboratory tests '4 pounds 
of Derridis plus 8 ounces of spreader to 177 imperial gallons of spray 
killed 54 percent of the first instars in 24 hours and 80 percent in 48 
hours. Of the second instars 20 percent were killed in 24 hours and 44 
percent in 48 hours. In another test Derridis, 4 pounds, plus 8 ounces of 
spreader to 100 imperial gallons of spray, killed 5.3 percent of the first 
instars in 24 hours and 42 percent in 48 hours. Derrisol proved a complete 
failure either as a contact or a stomach insecticide. In field tests Der- 
ridis at 4 pounds to 100 imperial gallons gave a control of 4.93 percent 
during 2 weeks and 7.64 percent during 1 month against Heliothis obsoleta 
on citrus trees. .Derrisol at 1:500 was very disappointing. 
Re id (345) in 1936 reported that the strengths of derris- or pyrethrum 
-dust mixtures recommended for the common species of cabbage worms were not 
effective in controlling the larvae of the corn earworm. In summarizing 
results obtained at Charleston, S, C., during the fall and winter of 1937- 
38, Reid ( 346 ) stated that a population consisting of the cabbage looper 
and various Agrotinae (principally the corn earworm and several species of 
climbing cutworms) can be controlled effectively by the use of a dust mix- 
ture consisting of calcium arsenate and hydrated lime (3:1) prior to the 
heading of the plants, followed by applications of a pyre thrum- talc-dust 
mixture containing 0.3 percent of total pyrethrins, or a derris-clay-dust 
mixture containing 1,0 percent of rotenone, at 10-day intervals after the 
plants have headed, provided the plants had been well protected against 
cabbage worms before being thinned or transplanted. The pyrethrum-dust 
mixture and the derris-dust mixture were most effective against the cabbage 
looper, and the calcium arsenate-dust mixture most effective against the 
Agrotinae. These results are also reported by the United States Depart- 
ment of Agriculture, Bureau of Entomology and Plant. Quarantine ( 446 ) in 
1938. 
Turner (420) in 1936 reported that the derris spray recommended for 
European corn borer control will not affect the corn earworm. 
Laboratory and field tests led to the conclusion that "one can safely 
give up hope of controlling this species by means of derris powder." Lar- 
vae having more than one-third of the body length covered with rotenone 
did not die and developed normally. -- Van der Vecht ( 454 ) in 1936. 
The Georgia Experiment Station ( 156 ) in 1938 reported that during the 
early summer of 1937, in several parts of the State, tomatoes suffered 
severe injury from the corn earworm. Some growers resorted to rotenone 
dusts, "but the corn earworm is known to bo peculiarly resistant to this 
material." 
Gunderson (173) in 1938 recommended derris for the control of the corn 
earworm. Flour, sulfur, pearl dust, gypsum, and other carriers are given 
as diluents. A 1-percent-rotenone dust was generally strong enough for all 
needs. Dorris spray, 5 pounds per 100 gallons, also controlled this pest. 
