26 BULLETIN 1472, U. S. DEPAKTMENT OF AGEICULTUKE 
INORGANIC COMPOUNDS 
Some of the inorganic compounds tested exhibit repellent action 
for a few days. For example, antimony trichloride is repellent for 
two days, bleaching powder for three days, copper sulphate for three 
days, and potassium sulphide for two days. Even the odorless and 
chemically inactive powder kaolin, for the first day of exposure, 
repels three-fourths of the screw-worm flies normally present. The 
strong repellent action of copper carbonate, which persists through- 
out the five days of exposure, is one of the most puzzling results 
obtained in the investigation, and required further testing. None 
of the inorganic compounds are effective in preventing infestation. 
No Cochliomyia flies emerged from jars treated with borax or lead 
acetate. 
ORGANIC PRODUCTS 
ESSENTIAL OILS 
The following essential oils when undiluted exhibit a coefficient 
of attractiveness toward screw-worm flies of 10 or less: Star anise, 
9.8; bergamot, 6; cade, 4.9; cinnamon, 10; citronella (Ceylon), 2.8; 
clove, 9.5; clove bud, 6.1; coriander, 5; rose geranium, 8; nutmeg, 
9.7; pennyroyal, 9.3; spearmint, 7.6. Tests with Java citronella oil 
and also with citronella oil of unknown geographical origin show 
them to have only moderate repellent value (coefficients 75 and 19, 
respectively) so that the high repellent value found for Ceylon 
citronella oil requires confirmation. In addition to the above oils, 
camphor by-product, cassia, copaiba, cumin, fennel, hemlock, and 
sassafras exhibit good repellent action (coefficient about 10 or less) 
for the first and second days of exposure only. 
None of the essential oils were successful in preventing infestation, 
but whether the infestation was by Cochliomyia or not is difficult 
to say because the emergence data are very meager. There was no 
emergence of screw-worm flies, however, from meat treated with the 
following oils: Star anise, bergamot, cade, camphor, cedar leaf, 
cinnamon, citronella, clove bud, nutmeg, pennyroyal, sassafras, or 
thyme. 
PATTY OILS 
Peach-kernel oil is a good repellent for the first two days of exposure 
only. None of the fatty oils prevents infestation. 
MISCELLANEOUS VEGETABLE PRODUCTS 
Clove powder, derris, and pyrethrum are effective repellents for 
the entire five-day period. Cinnamon powder is effective for the 
first two days, as are also sassafras bark and wormseed; and lupulin 
powder is effective over a three-day period. A single test with 
powdered deer-tongue leaves indicates that they have considerable 
repellent value. 
Although clove powder, derris, and pyrethrum did not prevent 
infestation, this was by species other than the screw-worm fly, as 
there was no emergence of Cochliomyia from any of the jars treated 
with these materials. The alcoholic and kerosene extracts of pyre- 
thrum also prevented emergence of Cochliomyia. 
