344 
percent of the pretreatment level, 
whereas the fly counts remained un- 
changed around the untreated dairy. 
The same degree of control was main- 
tained week after week until in Octo- 
ber, when the fly season had practi- 
cally ended, observations were discon- 
tinued. Similar results were obtained 
around other dairies. Thus a single 
thorough treatment with DDT caused 
immediate reduction in fly populations 
of over 95 percent under the most 
dificult of circumstances, and _ this 
degree of control persisted for the en- 
tire season. Ifsimilar results could be 
obtained around military installations, 
one of the most serious military prob- 
lems could be largely solved. 
The Orlando Air Base and the 
Fourth Service Command Corps of 
Engineers headquarters at Atlanta, 
Ga., cooperated in conducting similar 
tests in military installations. Spec- 
tacular results were also obtained un- 
der these conditions. On the strength 
of these studies, together with the 
elaborate studies which were still un- 
derway in the laboratory against both 
flies and mosquitoes, the potentialities 
of DDT residue treatments for fly con- 
trol was called to the attention of Army 
and Navy Personnel and Public Health 
Service workers. In 1944 the Army 
and Navy began employing DDT for 
fly control] in many parts of the world, 
and almost everywhere reports indi- 
cated excellent results. 
This means much to us in the United 
States, but even more to the people of 
places in the world where a high per- 
centage of the population might die 
as a result of fly-borne diseases. DDT 
or some similar insecticide used as a 
residual treatment can help solve sani- 
tation and health problems everywhere. 
Mites (Chiggers) 
Most of us at one time or another 
have experienced the discomfort 
caused by one of our smallest arthro- 
pod parasites—the larval stage of mites, 
commonly called chiggers or red bugs. 
Fortunately, in the Americas our chief 
concern with this pest is the irritation 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
caused by the bite. This alone, 
however, was sufficient reason to 
undertake intensive research to develop 
more effective methods of control. 
In the fall of 1942 medical officers 
participating in Army maneuvers in 
Louisiana and certain other southern 
States reported a larger number of 
hospitalizations of military personnel 
due to infections resulting from chigger 
bites than for any other cause. Later, 
however, our armies in the Pacific 
and in the China-Burma-India theater 
experienced outbreaks of scrub typhus 
or Tsutsugamushi disease, transmitted 
by mites closely allied to the species 
found in this country. Although the 
disease was fairly well known before 
the war, its potential importance was 
not fully realized by our scientists and 
medical men. Fortunately, when seri- 
ous outbreaks of mite typhus occurred 
among various military units in 1943 
and 1944, we had already developed 
an effective means of protecting indi- 
viduals from the vector. 
When the mite typhus problem be- 
came acute in several war areas, the 
U. S. A. Typhus Commission under- 
took extensive investigations on the 
vectors of this disease and Australian 
scientists also concentrated on the 
mite problem. At the suggestion of 
the Typhus Commission our work on 
mites, carried out in close cooperation 
with that agency and the Office of the 
Surgeon General, was _ intensified. 
Capt. R. C. Bushland, formerly in 
charge of the laboratory phases of the 
louse project at Orlando, had entered 
the Army. He was attached to the 
Typhus Commission staff and assigned 
to the miticide aspects. As he devel- 
oped the clothing impregnation meth- 
od of mite control under field conditions 
using dimethyl] phthalate, the work 
on new, more effective miticides was 
under way at Orlando by Fred M. 
Snyder, F. A. Morton, J. P. Linduska, 
Pvt. H. F. Cross, and others. 
The objective was to develop a miti- 
cide which when impregnated in 
clothing would protect the individual 
even after the clothing was washed. 
