METHODS DIRECTED AGAINST ADULT MOSQUITOES 
305 
of soft natron soap with the addition of 
methyl alcohol. 
In India, Sinton and Wats (1935) tested 
the efficiency of various insecticidal sprays 
in the destruction of adult mosquitoes and 
found that a solution of one part of a 
standardized concentrated extract of pyre- 
thrum flowers (Pyrocide 20) in 19 parts of 
refined kerosene gave results approxi¬ 
mately equal to those of the best pro¬ 
prietary brands at about half the cost. 
These authors stated that the spray was 
improved by the addition of 5 per cent oil 
of citronella, \ to 1 per cent oil of sassafras 
or 4 to 5 per cent oil of pine. Manifold 
(1939) remarked that a popular formula 
for the spraying of huts, barracks and 
tents was made up of paraffin oil, second 
grade, 124 oz., extract of pyrethrum 2 oz., 
carbon tetrachloride 4 oz., oil of citronella 
8 oz. and gasoline (Petrol) 22 oz. 
Sprays of pyrethrum extract (Pyrocide 
20) in 19 parts of kerosene yielded satis¬ 
factory results in many anti-mosquito cam¬ 
paigns. Chopra (1938) added one part 
of pine oil to the mixture; Covell, Mulligan 
and Afridi (1938) obtained favorable cost 
comparisons with temporary anti-larval 
measures; de Burca (1939) believed re¬ 
duced incidence of malaria among troops 
in a cantonment followed a spray program 
and Russell and Knipe (1939) concluded 
that the weekly spraying of houses and 
sheds prevented malaria transmission to 
a marked extent. Barreto (1929) added 
pyrethrum to the kerosene and carbon 
tetrachloride spray used originally in the 
Rio de Janeiro yellow fever epidemic in 
order to destroy adult anopheles in Brazil. 
In the United States outdoor gatherings 
have been provided temporary protection 
from mosquito attack by using sprays. 
Ginsburg (1935) reported a series of satis¬ 
factory trials of a pyrethrum larvicide 
spray for this purpose. In one formula an 
emulsion of 100 gallons of kerosene, con¬ 
taining extract of pyrethrum in the 
amount equal to 100 pounds of flowers, 6 
pounds of “Gardinol” concentrated wet¬ 
ting agent and 50 gallons of water was 
diluted with 10 or 12 parts of water. 
Power sprayers applied the diluted mate¬ 
rial to the vegetation and as a mist in the 
area to be protected. In Florida, King, 
Bradley and McNeel (1937) obtained a 
high degree of mosquito repulsion in an 
uncleared area with pyrethrum extract, 
pine tar oil, oil of citronella and kerosene 
sprays. In a cleared area, however, none 
of these sprays was effective during the 
first mosquito flight period. The behavior 
of the insects suggested that they were 
affected chiefly upon coming in close con¬ 
tact with the sprayed vegetation rather 
than by odors carried through the air. 
Among the methods used for destroying 
disease transmitting mosquitoes in aircraft, 
Symes (1937) recommended spraying the 
compartments immediately after depar¬ 
ture from an airport with a mixture of 1 
part concentrated extract of pyrethrum, 
16 part of white kerosene and 68 parts of 
carbon tetrachloride. Ross (1938) de¬ 
scribed the use of aqueous base and carbon 
tetrachloride extracts of pyrethrum in air¬ 
craft of the Imperial Airways. Applica¬ 
tion was made with dry mist vaporizers 
and sprayers operated by a soda water 
siphon bulb containing carbon dioxide 
under 400 pounds pressure. 
Griffitts (1933) demonstrated the ability 
of mosquitoes to enter the United States 
from Central America in aircraft and en¬ 
dorsed the procedure of fumigating air¬ 
planes under emergency conditions and 
preceding overhaul with as much as 8 
ounces of hydrocyanic acid per 1000 cubic 
feet in the form of Zyklon discoids. 
Williams (1940) outlined the procedure 
of the Public Health Service to prevent the 
introduction into the United States of mos¬ 
quitoes infected with yellow fever from 
South American ports; to prevent the in¬ 
troduction of A. gambiae from eastern 
South America; and to prevent the intro¬ 
duction of any anopheles from the west 
coast of the United States into the Hawai¬ 
ian Islands. The methods of spraying the 
fuselage of all planes from South America 
with a concentrated pyrethrum spray (2 
grams pyrethrins in 100 cubic centimeters 
of light oil) as described by Williams and 
Dreesen (1935) and by Welch (1939) was 
changed to spraying the interior of the 
