INSECT CONTROL INVESTIGATIONS—KNIPLING 
The Australians had found that cloth- 
ing treated with dibutyl phthalate, 
chemically related to dimethyl phtha- 
late, was effective even after it was 
laundered. DDT which had given us 
an effective weapon for so many of our 
other problems was of no value in 
controlling mites. 
A. H. Madden and A. W. Lindquist 
undertook the early investigations on 
mites or chiggers. The objective 
was to develop a treatment which the 
individual could use to protect him- 
self from mite attack. As with the 
louse and insect-repellent projects, 
human subjects acted as guinea pigs. 
These research subjects exposed them- 
selves to chiggers in highly infested 
areas. Those wearing untreated cloth- 
ing knew they were in for hours of 
irritation which the chiggers would 
cause. The others were only hopeful 
that the treatment applied to them 
would be a good one. Most tests were 
conducted in areas where untreated 
men could be expected to obtain up to 
200 chigger attachments after a 2-hour 
exposure. 
Many types of treatments were 
tested to protect individuals from 
chiggers, including insect repellents 
applied to the skin and dusts applied 
in clothing. The most significant ad- 
vance in mite control, however, was 
the work on clothing treatment. 
When socks and army uniforms were 
treated with dimethyl phthalate or 
some of the other repellents and in- 
secticides, and worn by subjects in 
heavily infested chigger areas, com- 
plete protection was obtained. This 
single treatment remained effective for 
several weeks. Good control was ob- 
tained also by spraying the repellents 
on the clothing. Even simpler meth- 
ods were tried and it was found that 
excellent control could be obtained by 
applying a repellent barrier to the 
socks and all the openings of the 
clothing. 
In evaluating the different miticides, 
definite steps were followed. Patches 
of cloth of the kind worn by service 
men were treated, and mites were 
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placed on the treated cloth. If the 
mites were killed or immobilized 
within 15 minutes, the chemical was 
studied further to determine whether 
the treatment remained effective after 
the clothing was washed or laundered. 
Several thousand materials were eval- 
uated in this manner (pl. 6, fig. 2), and 
the more promising of those which 
were not too toxic or possessed no 
objectional features were considered 
for practical tests. Samples of these 
were forwarded by the Typhus Com- 
mission to their men in the Pacific 
and to those in the China-Burma-India 
theater. The same materials were 
also tested further by the men at 
Orlando. The Chemical Warfare 
Service also investigated miticides and 
concentrated on binders such as chlo- 
rinated paraffins which might prolong 
the action of the mite treatments 
applied to clothing. 
These studies produced a number of 
materials which were highly effective. 
Benzyl benzoate was among the 
best that were know to be safe to use 
and that could be made available 
without much delay. Dibutyl phthal- 
ate was generally effective, but the 
degree of protection it afforded was 
somewhat erratic. Because of short- 
ages of benzyl benzoate, the Office of 
the Quartermster Corps requested 
tests with a combination of this mate- 
rial and dibutyl phthalate and these 
tests indicated that a 50-50 mixture 
of the two miticides was approximately 
as good as benzyl benzoate alone. 
This mixture is now the Army’s 
standard miticide. When the war 
ended, work was underway on a num- 
ber of materials which, on the basis 
of preliminary tests, were even superior 
to benzyl benzoate. 
Thus other important weapons were 
developed which protected our fight- 
ing forces from an enemy that exper- 
ience with isolated units had indicated 
could be as destructive as the Japs. 
Other Problems Investigated 
Fleas——Fleas, through the trans- 
mission of plague, have in the past 
