BUREAU OF ENTOMOLOGY AND PLANT QUARANTI \ E 27 
rides to meet war needs. Many synthetic organic compounds have 
been prepared for testing as insect repellents, lousicides, and mos- 
quito larvicides. Investigational work was reported in 88 published 
articles, and 30 United States patents covering new insecticides and 
methods oi application were granted. 
DDT INTENSIVELY INVESTIGATED 
As indicated elsewhere in (his report. DDT has proved amazingly 
effective against a number of agricultural insects and is bring used 
by the armed forces in ever-increasing amounts for the control of 
body lice and as a partial replacement for pyrethruni in aerosols. 
The Division of Insecticide Investigations has been intimately as- 
sociated with the development of DDT for these purposes and has 
taken an active part in furthering its manufacture in this country. 
Specifications have been developed for a satisfactory grade of DDT. 
and manufacturers were assisted in meeting these standard-. An 
extensive research program on DDT for the armed forces is being 
carried on under a transfer of funds from the Office of Scientific lie- 
search and Development. Suitable preparations of DDT also arc 
being developed for use against agricultural pests. 
AEROSOL DEVELOPMENT CONTINUED 
With the. increasing demand by the Army and Navy for aerosol 
bombs for the control of malaria mosquitoes and houseflies, it has 
been necessary to develop substitutes for the limited supplies of py 
rethrum and Freon-12 (dichlorodifluorom ethane). A formula con 
taininga considerably decreased amount of pyrethrins and another in- 
secticide was worked out. A mixture of propane and butane was 
shown to be satisfactory and safe as a partial substitute for Freon-12. 
The aerosol method has also been found effective for applying other 
insecticides in greenhouse and field against certain agricultural pests, 
as well as for applying hormones to plants. 
SUBSTITUTES AND EXTENDERS FOR WAR-SCARCE INSECTICIDES SOUGHT 
Inasmuch as imports of roten one-bearing root- and pyrethrum have 
been greatly curtailed and other insecticide supplies restricted, the 
development of substitutes or means of extending the supply has be- 
come of great importance. A number of synthet ic organic compounds 
have been found effective as synergist- for pyrethrum. It was show n 
that anethole can be substituted for geraniol and pimento-leaf oil for 
eugenol in Japanese beetle bait without adverse effect. Extracts of 
the plant Erigeron afflnds DC proved very toxic to houseflies and to 
some other insects. A mixture of soybean phosphatides and raw min- 
eral oil was found to be a satisfactory substitute for soybean oil as a 
spreader and adhesive for lead arsenate and nicotine bentonite sprays. 
PURE PYRETHRINS PREPARED 
A method was devised for the preparation of practically pure py- 
rethins from commercial pyrethrum extracts with very little Loss of 
pyrethrins. This pure material is completely soluble in Freon-12 and 
