EMULSIONS FOE JAPANESE BEETLE 
13 
the tangled root mass, but is appreciable in the aggregate. Experi- 
mental work has shown that it is much easier to kill the larvae in iris 
roots than in peony roots because of the difference in the distribution 
of the soil. Here, again, soil-absorption is apparently the limiting 
factor. A larva in the center of a cubic inch of soil is not affected to 
nearly the same extent by the dip as a larva in the center of a mass of 
soil and roots consisting of 1 cubic inch of soil mixed with 3 cubic 
inches of roots, when both are submerged in the same concentration of 
dip. In fact, the submergence of iris roots for 15 hours in a dip con- 
taining 0.5 cubic contimeter of ascaridole per 3 liters of water at 70° F 
completely killed the larvae in them; whereas twice this dosage was 
required for killing the larvae in peony roots under the same conditions 
of time and temperature. Incidentally the peonies were not injured 
by a dip of this greater 
strength when submerged 
for the time stated, but the 
added cost of the dip, while 
not prohibitive, led the 
writers to experiment with 
other toxic materials in 
emulsion as a control for 
the larvae infesting this 
particular plant. Of the 
materials tested in this con- 
nection carbon disulphide 
was found to be the most 
feasible. 
CARBON-DISULFIDE 
EMULSIONS 
EMULSION 1 
Experimental work 
showed that carbon disul- 
fide could be emulsified by 
soaps in general, and the 
writers found the old style 
rosin-fishoil soap to be the 
best for this purpose. It 
is a thick, heavy soap and 
must be heated with water to dissolve it. When it is availaole a 
stock soap solution can be made by adding 12.5 grams of rosin-fishoil 
soap to 87.5 cubic centimeters of water, heating until dissolved and 
allowing the solution to cool. Add 20 cubic centimeters of this stock 
solution to 50 cubic centimeters of carbon disulfide in an Erlenmever 
flask and agitate until the ingredients emulsify, which will require 
but a few minutes. Larger quantities, using the same proportions, 
may be emulsified with a butter churn or ice-cream freezer. The 
emulsion proper is white and has the consistency of thick cream. 
When added to water it disperses evenly and remains indefinitely in 
suspension. 
EMULSION 2 
Where the old style rosin-fishoil soap is not available a good 
emulsion may be made by mixing 0.5 cubic centimeter of oleic acid 
Peony root, divided longitudinally, showing infesta- 
tion by larvae of the Japanese beetle 
