-99- 
Derris was not effective against cutisroras. — Alabama Polytechnic 
Institute (10.) in 1 93 5. 
The South Carolina Agricultural Experiment Station ( 581 ) in 1935 
reported that experiments of the 1934-35 season indicated that a dust mix- 
ture of derris powder and clay, containing 0.5 percent of rotenone, v/as 
not so effective as the arsenicals against cutworms on cabbage. 
Tischler ( 413 ) in 1935 reported that studies on the heart rates of 
various insects (including tomato cutworms) showed that the rate of pul- 
sation was markedly decreased before the insects exhibited incoordinated 
movements. Other tests made with tomato cutworms led to the conclusion 
that derris inhibits oxygen utilization by the tissues and that its detri- 
mental effects are general, rather than specific to any organ. Derris 
must penetrate into the insect body to produce toxic effects. This fact 
was evidenced by the low toxicity of derris as a spray or dust to cutworms, 
which, however, are susceptible to derris when a water extract is injected 
into the blood stream. It is not understood why derris penetrates readily 
into some insects and into others with difficulty. Derris extract enters 
the insect body through the alimentary canal, the spiracles and tracheal 
system, and the external integument. Derris powder enters by way of the 
alimentary canal, and also is probably extracted by the water of the body 
exudates and of body fluids by a process of osmosis, and is then absorbed 
through the integument. 
White ( 480 ) in 1935 stated that derris is ineffective against cutworms. 
In 1936 and 1937 he (482) stated that neither derris nor pyrethrum, at the 
dilutions tested, had been effective in combating cutworms on cabbage. 
Reid ( 345 , 348 ) in 1936 reported that the strengths of derris or py- 
rethrum-dust mixtures recommended for the common species of cabbage worms 
were not effective in controlling cutworms on cabbage. Reid ( 346 ) in 1938 
summarized results obtained in insecticide tests directed against cabbage 
worms on cabbage grown at Charleston, S. C, during the fall and winter of 
1937-38. He reported that a cabbage worm population consisting of the cab- 
bage looper and various Agrotinae (principally the corn earworm and several 
species of climbing cutworms) was controlled with a dust mixture of calcium 
arsenate and hydrated lime (3:1) prior to the heading of the plants, follow- 
ed by applications of a pyrethrum- 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 experiment demonstrated that the pyrethrum and derris 
-dust mixtures were most effectivo against the cabbage looper and that the 
calcium arsonate-dust mixture was mo;-t effective against the Agrotinae. 
These results wore referred to in the 1938 annual report of the United 
States Department of Agriculture, Bureau of Entomology and Plant Quaran- 
tine (446). 
