362 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
compound is equal to carbon bisulphide as a general soil insecticide for 
the control of the egg, larva, and pupa. Considering its toxicity to the 
insect, it has the least deleterious action upon plants of any compound 
known when properly handled. Under the circumstances and in view of 
the lack of other chemicals of all-around value, the work has unavoidably 
centered upon a fundamental study of this compound and its effect upon 
the insect, the soil, and the plant. 
One of the first problems arising in connection with the Japanese 
beetle project consisted in devising a method of freeing the soil (destined 
for greenhouse potting purposes) of any stage of this insect. A complete 
report 2 of this work has been published, embracing a study of the fumi¬ 
gation of soil with carbon bisulphide in a closed container. The results 
indicate that the treatment of loose soil in a tight container by the in- 
terspersion of definite injections of liquid carbon bisulphide is a cheap 
and efficient method fdT this purpose when used at the rate of 13 fluid 
ounces per cubic yard of soil. It was found that the diffusion of the 
carbon bisulphide vapors throughout the soil varied directly with the 
depth from the surface of the soil and inversely with the lateral distance 
from the point of injection. The soil type when the soil was thrown 
loosely into the fumigating chamber was not a limiting factor. Soil 
moisture became a limiting factor when it approached the saturation 
point; the soil temperature impaired the efficiency of the method when it 
fell below 50° F. When used at the above rate, the treatment did not 
affect the subsequent growth of herbaceous plants. The method is now 
in general use by the nurseries within the infested area. In the same 
way as above a study was made of the fumigation of plants, with balls of 
earth about their roots, in closed containers. No difficulty was en¬ 
countered in killing any insects present (aside from those in puddled 
soils) but the aerial portions of the plants did not survive the treatment. 
When carbon bisulphide was injected into the soil of potted plants 
or about the crown of plants growing in the nursery row in concentration 
heavy enough to secure 100 per cent control, the plants were injured with 
the one outstanding exception of Japanese azalea. 
In view of the above results the writers began a series of fundamental 
experiments involving the use of carbon bisulphide with water as a 
carrying agent. It was found that 100 per cent control could be secured 
in practice but the mixture of carbon bisulphide and water was uncertain, 
due to the dependence of the concentration on the temperature of the 
2 Fleming, W. E. Fumigation of potting soil with carbon bisulfide for the control 
of the Japanese beetle. In N. J. Agr. Exp. Sta. Bui. 380. 
