58 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1952 
Promising results were also obtained with Systox, compound 923, 
OMPA, Metacide, and methyl ester pa ruth ion. 
The most effective material- tested against the variegated cutworm 
in Mississippi were endrin, TDK. DDT. and toxaphene. In '1 
excellent control of the pale-sided and granulate cutworms was ob- 
tained with toxaphene and toxaphene plus DDT; less effective ma- 
terial- included parathion, chlordane, and dieldrin. 
Ii was found that all of the formulations recommended for use 
against the boll weevil also gave excellent control of thrips at ap- 
proximately one-half to one-third of thai dosage. These materials 
include toxaphene. benzene hexachloride. heptachlor. aldrin. chlor- 
dane. and dieldrin. 
Fundamental Properties of Cotton Insecticides Studied 
In field-cage and Laboratory tests conducted at ( lollege Stat ion, Tex.. 
in cooperation with the Texas Agricultural Experiment Station it 
was found that calcium arsenate, toxaphene. and dieldrin had Longer 
residua] properties againsl the boll weevil than benzene hexachloride. 
aldrin. chlordane. or heptachlor. although the action was slower. 
Heptachlor. dieldrin. aldrin. and chlordane. each killed a high per- 
centage of boll weevil- developing inside cotton squares. Benzene 
hexachloride was much Less effective in this respect than the other 
materials. 
Applied at one-third pound per acre EPN was effective againsl the 
boll weevil in laboratory and field-cage tests bu1 failed to give control 
in some held experiments. It also failed to kill boll weevils inside 
cotton squares. 
A fter t w ■<) dusi applications the average total insect population over 
a period of about one month was reduced, as com] tared to the untreated 
check, by the following percentages: Dieldrin 80, aldrin 77. DDT 75, 
toxaphene 74. benzene hexachloride 66, EPN 61, and parathion 58. 
After three spray applications, the average total beneficial insect 
population over a dry, hot period of about 2 month- was reduced under 
that of the untreated check by the following percentages: Toxaphene 
17. aldrin 3, and dieldrin 11. 
When used againsl the garden webworm EPN, parathion, and 
methyl parathion each gave s <'> percent mortality or higher at rates 
of one-third pound or less per acre in cage tests. 
Of eighl material- tested in cages againsl the sail -marsh caterpillar, 
EPN and parathion each caused a mortality of more than 90 percent 
at one hal f pound per acre. 
EPN at one-third pound per acre was the most effective of L6 
materials tested againsl the yellow-striped armyworm. 
New chemicals tested againsl t he boll weevil included endrin, methyl 
parathion, Insecticide 3960 XI I. malathon, Metacide. com pound L795, 
aimethyl potasan and compound Q L29. 
New chemical- tested in the laboratory againsl the cotton aphid 
included OMPA, Systox. malathon. and dimethyl potasan. 
Biochemical investigations to determine the manner in which in- 
secticides kill various cotton Insects, showed thai the fat content 
of the boll weevil increases as the Beason progresses and. as a rule. 
the toxicity of the chlorinated hydrocarbons decreases. Field col- 
lected boll weevils averaged about 6 percent fat in .June and increased 
