386 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
with clay. No time was saved however by the use of the paper. A 
pound of carbon disulphid at a cost, say of 40 cents, is sufficient for 
treating 75 to 100 trees. It is needless to add that the liquid is volatile, 
explosive in the presence of a flame, and poisonous, so care should be 
taken in handling it. 
LUBRICATING-OIL EMULSION AS A CONTROL FOR CHRYSOM- 
PHALUS AONIDUM IN GREENHOUSES 
By C. A. Weigel and Miss B. M. Broadbent, 
Fruit Insect Investigations , Bureau of Entomology, Washington , D. C. 
Abstract 
The need for a more efficient contact insecticide for hardy ornamentals in green¬ 
houses suggested the desirability of testing lubricating oil emulsion which had proved 
so effective for white flies in Florida, and recently against San Jose scale. In 1922 
young Kentia palms, heavily infested with the Florida red scale, Chrysomphalus 
aonidum L., were sprayed one, two, and three times in succession with 1:50 (or 1-1/3%) 
“Boiled,” and “Cold-stirred” emulsions. Formulas for each are given and appeared 
equally effective. In 1923 a miscellaneous group of infested plants, including Kentia, 
Phoenix, Aspidistra, Ficus, Laurus nobilis, Aucuba Japonica, and citrus sp. were 
sprayed with “Boiled” emulsion. The 1:32 and 1:25 dilutions left the foliage greasy 
and yellowed the palm fronds. Spraying once with the 1-1/3 % emulsion if thorough¬ 
ly done gave a satisfactory control without injury to the plants. Results of experi¬ 
ments are presented in the table. 
During the past ten years lubricating-oil emulsion has been used 
extensively in Florida for the control of white flies and scale insects in 
citrus orchards. More recently it has proved very satisfactory as a 
dormant spray for the control of San Jose scale in apple orchards in the 
Ozark region of Arkansas and Missouri. 
The remarkable insecticidal efficiency obtained from a 2% emulsion, 
and the fact that it contained very little oil suggested the possibility of 
using this material on ornamental greenhouse plants infested with scale 
insects, because the margin of safety in the use of insecticides under 
glass is narrower than out of doors. The development of a contact in¬ 
secticide having such qualities would meet a constant demand on the 
part of greenhouse men for a remedy which would be more effective 
against scale insects than nicotine soap solutions or other contact sprays 
and would be suitable for treating palms, Ficus and other hardy plants. 
Moreover, it could be used where circumstances would not permit fumi¬ 
gation with hydrocyanic-acid gas. 
During the summer of 1922 a number of young Kentia palms heavily 
infested with the Florida red scale, Chrysomphalus aonidum Linn., were 
available for such a test. Preliminary experiments were undertaken to 
