338 
for application by means of aircraft. 
Largely owing to developments by the 
Bureau of Entomology and Plant 
Quarantine and the Tennessee Valley 
Authority, airplanes had been used ex- 
tensively in connection with the con- 
trol of insects attacking agricultural 
crops and anopheline larvae. In the 
first efforts to apply DDT from the air, 
dusts were employed. In collabora- 
tion with TVA scientists it was shown 
that DDT applied in this way was 
effective, but the physical properties 
of dusts containing a high percentage 
of DDT were such that they were diffi- 
cult to apply with existing equipment. 
Efforts to apply DDT from the air 
were accordingly concentrated on the 
development of sprays. C. N. Hus- 
man, engineer, and O. M. Longcoy, 
pilot, developed experimental models 
of aerial sprayers which would deliver 
and distribute about 2 quarts per acre 
of sprays having rather small droplets. 
All early experimental work was done 
with a Piper Cub plane (L-4) equip- 
ped with sprayers (pl. 3, fig. 2). 
Field tests on natural breeding areas 
with such equipment, after experimen- 
tal tests on larvae in ice cream cups, 
demonstrated that good control of 
larvae resulted with a 5-percent DDT 
oil solution or emulsion applied at the 
rate of 1 to 2 quarts per acre. 
Since little was known about the 
application of liquid insecticides from 
airplanes, the experimental work on 
the development of DDT larvicide 
sprays involved studies with various 
types of equipment, relation of par- 
ticle size to effectiveness of the spray, 
relative effectiveness of different for- 
mulations, optimum concentrations of 
DDT in the spray, and many other 
factors. The potentialities of the uti- 
lization of aircraft for dispersing DDT 
sprays was called to the attention of 
the Army Air Forces Board of Orlando, 
Fla., and as early as December 1943 
cooperative tests were undertaken uti- 
lizing fast combat planes equipped 
with standard Chemical Warfare Serv- 
ice devices. Studies on many aspects 
of the aerial dispersal problem contin- 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
ued “during 1944”and*°1945,° and a 
number of other agencies undertook 
investigations during that period in- 
cluding several branches of the Army, 
both at home and overseas; Tennessee 
Valley ‘Authority; U. S. Navy; Na- 
tional Defense Research Committee; 
and others. Consequently, by 1945, 
planes ranging in size from L-4’s to 
C-47 transports were equipped with 
improved aerial spray equipment, and 
the armed services were prepared to 
blanket DDT over mosquito breeding 
areas involving, if necessary, thousands 
of acres. 
KILLING OF ADULT MOSQUITOES 
The complete story of the important 
research on DDT for controlling adult 
mosquitoes, if related in detail, would 
require more space than is allowed for 
the entire topic under discussion; 
therefore, only the high spots of this 
subject will be reviewed. ‘The investi- 
gations designed to improve on mate- 
rials and methods to kill adult mosqui- 
toes involved research on aerosols and 
sprays and on residual treatments. 
The work on adults was under the 
supervision of A. W. Lindquist, and 
his assistants included J. B. Gahan, 
H. O. Schroder, A. H. Madden, H. G. 
Wilson and others. B. V. Travis and 
F. A. Morton who were investigating 
repellents also took an active part in 
the early studies on the control of adult 
mosquitoes. ‘The many chemical as- 
pects involved in these investigations 
were under the supervision of Howard 
A. Jones, who was assisted by Miss 
Helen Fluno, Corp. C. T. McCollough, 
and others. 
Aerosols and sprays for use indoors.—As 
early as 1942 the armed services were 
already employing the famous aerosol. 
bomb for the control of flies and mos- 
quitoes. This unique principal of 
dispersing aerosols was developed by 
L. D. Goodhue and William Sullivan 
of the Bureau of Entomology and 
Plant Quarantine. The problem at 
Orlando was to explore the possibility 
of utilizing DDT in the aerosol for- 
