INSECT CONTROL INVESTIGATIONS—KNIPLING 
that control of adult mosquitoes was 
possible through the use of this equip- 
ment. 
The crucial tests on adult mosquito 
control on an area basis employing 
airplanes were conducted in Panama. 
The Office of the Surgeon General, 
U. S. Army, arranged for such tests 
against tropical Anopheles and other 
mosquitoes. In March of 1944 Mr. 
Lindquist and Mr. Husman of the 
Orlando staff were issued Army orders 
to proceed to Panama with equipment 
and materials. The tests were made 
in cooperation with Army personnel in 
Panama. If tropical Anopheles could 
be controlled in jungle areas with DDT 
sprays applied from the air, the Army 
would try the method on a large scale 
against other species in various parts 
of the world. 
Two tests were made on 50-acre 
plots, each using the Husman-Longcoy 
spray unit on an L-4 plane already 
mentioned (pl. 3, fig. 2). The results 
were phenomenal. A reduction of at 
least 95 percent of adult Anopheles and 
other mosquitoes was indicated, and 
complete control of larvae was ob- 
tained when breeding areas were 
present in the area sprayed. For at 
least a week the population of the 
mosquitoes in the treated area was 
greatly reduced. Thus the effective- 
ness and feasibility of adult mosquito 
control on an area basis were estab- 
lished. 
I shall not attempt to review further 
developments except to state that im- 
proved spray equipment consisting of 
spray booms placed under the wings 
of the aircraft were developed for use 
on L-4 and PT-17 planes. Prelimi- 
nary studies were also undertaken with 
smokes and aerosols dispensed through 
the exhaust pipe of aircraft. Other 
agencies made important contribu- 
tions in developing aerosol spraying for 
mosquito control. The ‘Tennessee 
Valley Authority and Division 10 of 
the National Defense Research Com- 
mittee concentrated on and developed 
the exhaust type of equipment which 
is now widely employed; the Army 
341 
Air Forces developed spray equipment 
for B—25 bombers and C-47 transports; 
and the Navy, in cooperation with the 
Orlando personnel, developed spray 
equipment for the TBM and TBF 
airplanes (pl. 5, fig. 1). Overseas 
units in the Army and Navy inde- 
pendently constructed equipment for 
aerial dispersion of DDT. 
No phase of the insect-control work 
created greater or more widespread 
interest than did the aerial spray pro- 
gram for destruction of mosquito 
larvae and adults. Special missions 
organized by the Army and Navy were 
sent to different areas to conduct prac- 
tical field tests with various kinds of 
equipment. One such mission in 
Panama was discussed by my col- 
league, H. H. Stage, in an article in 
the 1947 Smithsonian Report. 
Aerial dispersion provided an effec- 
tive means of quickly bringing under 
control the mosquitoes already present 
in infested areas. The destruction of 
the adults in 24 hours or less, including 
any that might be infected with dis- 
eases, eliminated overnight the pos- 
sibilities of disease transmission. Con- 
trol of larvae at the same time meant 
that in large areas at least 3 weeks of 
protection from mosquito disease trans- 
mission was assured. 
The Army and Navy in 1945 ac- 
tually treated entire islands in the 
Pacific and extensive areas in other 
war theaters for the control of mosqui- 
toes and flies. At present, civilians 
are treating large areas for control of 
adult mosquitoes and other related 
insects. The research on dispersion of 
aerosols from the ground also went 
forward, sponsored by Division 10 of 
the National Defense Research Com- 
mittee and other agencies. Such de- 
vices, greatly improved, are now in- 
cluded among the weapons for elimi- 
nating various insects attacking man. 
Five years ago very few biologists 
could have visualized the future de- 
velopment of such methods of control- 
ling the insect pests and disease car- 
riers in dense tropical jungles or on the 
open tundra of the far North. 
