EMULSIONS FOR JAPANESE BEETLE 7 
TOXICITY OF WORMSEED-OIL EMULSIONS 
The dip made with emulsion of oil of wormseed was tested in three 
different ways: (1) Larvae, free from soil, were submerged in the dip 
for varying periods to determine the time necessary to kill them at 
various temperatures. (2) A similar series of exposures was made with 
larvae embedded in soil. (3) Plants infested with the larvae were 
immersed in the dip under varied conditions of temperature and 
length of exposure to determine the toxicity of the material to the 
larvae under natural conditions and the resistance of the plants to the 
insecticide. The entire crop of one of the local nurseries was treated 
in this test, which was carried out under commercial conditions. 
TOXICITY OF WORMSEED OIL TO JAPANESE BEETLE LARVAE 
The toxicity of the emulsions of wormseed oil to the larvae of the 
Japanese beetle was determined by submerging the larvae, free from 
soil, in the dip for varying periods of time at various temperatures. 
Emulsion 1 as listed in Table 2, and emulsions 3 A and 9A of Table 3, 
were employed in these tests in the proportions of 1 cubic centimeter 
of ascaridole to 6 liters of water. The wormseed oil employed assayed 
75 per cent ascaridole by the acetic acid method already described. 
The results of these tests are presented in Table 4. It will be ob- 
served that the best results were obtained when the temperature of 
the dip was maintained at 65° or 70° F. Lower temperatures reduced 
the toxicity of the material. 
Tab le 4. — Toxicity of wormseed-oil emulsions to Japanese beetle larvse (not in soil) 1 
Temperature 
Percentage of larvae killed by immersion in dip for hours specified 
of dip 
3 
4 
5 
6 
7 
8 
9 
12 
15 
18 
21 
24 
o F 
50 
° C. 
10 
16 
18 
21 
50 
75 
100 
100 
75 
100 
100 
100 
75 
100 
100 
100 
75 
100 
100 
100 
100 
100 
100 
100 
60 

25 

100 
65 
50 
50 
25 
75 
100 
100 
100 
100 
70 
1 A total of 500 larvae were used in the tests on which this table is based. In each instance here recorded 
the larvse were immersed for the specific time, and the percentage of those killed is tabulated. In each 
case the dip contained ascaridole in the proportion of 1 cubic centimeter to 6 liters of water. 
TOXIC STABILITY OF WORMSEED-OIL EMULSION 
In the course of the experimental work several samples of the 
emulsion of various ages accumulated. These were tested under 
identical conditions and all on the same day in order to determine 
whether the stock emulsion on standing had undergone any change 
which might affect its toxicity. The results of these tests are given 
in Table 5. It will be observed that the emulsion did not decrease 
in toxicity within the space of 40 days. The results indicate that the 
toxicity will persist indefinitely if the emulsion is kept in a cool 
place, since the chemical change, if any, is slow. 
