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and small field-plot tests at El Paso, Tex., stated that derris was 
by far the most effective insecticide used. In addition to prevent- 
ing the young larvae from entering the bolls, derris was a repellent 
and decreased oviposition on the dusted bolls. 
Chapman and Cavitt, in a typewritten report tb r the Division of 
Cotton Insect Investigations, Bureau of Entomology and Plant Quaran- 
tine, gave the following results of laboratory tests with cube and 
other insecticides in Presidio, Tex., in May 1934-. Petri dishes 
with a small coin placed in the center were given a light covering of 
dust a.plisd with a small hand gun' in a dusting chamber. Approximately 
25 newly hatched first instars were placed in the undusted circle, 
which had been covered by the coin, and were allowed to crawl into 
the dust. Examinations for mortality were made at intervals ranging 
from l/2 hour to 2-1/2 hours. Four dusted dishes and a check were 
used for each test. In series I, 13 insecticides, including several 
samples of derris from different sources, cube, and pyre thrum, were 
used. The derris samples contained from 1 to 8 percent of rotenone 
and the cube contained 6 percent of rotenone. All the samples were 
mixed with flour in equal proportions. Pyre thrum showed no kill, 
"while many of the derris samples and the cube root showed as much 
as 100 percent kill at the 2-l/2 hour examinations. \The checks 
showed no mortality." 
In series II, the above-mentioned samples were all diluted with 
flour 1:3. "At the end of 2 hours there were few larvae alive in 
any of the tests and in one sample there was 100 percent mortality." 
In series III, the two samples of derris that gave the best results 
in Scries IiandTTI and the- cube were selected. Dust No. 1: Derris, 
claimed to contain between 5 and 7 percent of rotenone, was mixed 
with flour 1:7. Diluted dust therefore contained approximately 0.75 
percent of rotenone. In 2-l/2 hours 86,5 percent of the larvae irere 
dead. Dust No. 7: Derris containing 5-l/8 percent of rotenone was 
mixed with flour 1:7. Diluted dust therefore contained approximately 
5/8 percent of rotenone. Eighty percent of the larvae were killed 
in 2-1/2 hours. There was no mortality in the checks during the 
same period. Dust No. 12v Cube containing 6 percent of rotenone 
was mixed with flour 1:7. Diluted dust contained 0.75 percent of rot- 
enone. fill the larvae were dead in 2-1/2 hours. 
Fenton, Chapman, Owen, and Fife (131) in 1934 reported the results 
of laboratory and field tests with insecticides at Pr sidio, Tex. 
In the laboratory tests for larval mortality, green bolls grown under 
cages and worm-free were usee 1 . They were cut from the plants with 
attached stems, which were inserted through carboard covers over j^rs 
of water. The bracts were removed and 10 eggs abo'it ready to hatch 
were inserted beneath the involucre. The bolls were then thoroughly 
dusted and were examined 4 to 5 days later. Powdered derris (rot- 
enone, 4.. 8 percent) was the most effective material in laboratory 
tests. It reduced the number of worms per boll over that of the 
checks 89 percent. 
The field tests were confined to small groups of plants. All 
the bolls of suitable size were tagged and the infestations "stepped up' 
