June, ’24] 
WEIGEL AND BROADBENT: OIL EMULSION 
I 
387 
determine whether this insecticide could be used safely at a strength 
which would kill the insects. Both the “boiled” and “cold-stirred” 
emulsions were prepared according to the following formulae 1 using 
Junior Red Engine Oil and potash fish-oil soap as ingredients. 
Boiled Emulsion Formula 
Paraffin oil.gallons 2. 
Water .gallons 1. 
Fish-oil soap.pounds 2. 
Cold-stirred Emulsion Formula 
Paraffin oil.gallons 2. 
Water.gallons 1. 
Fish-oil soap.pounds 8. 
In each case these stock emulsions were then diluted 1:50 (or 1-JJ 
per cent), and applied to the infested plants by means of a one-gallon 
compressed-air sprayer. Some of these plants were sprayed two or three 
times in succession at short intervals in order to determine the relative 
efficiency of such treatment. 
The results of the 1922 experiments, 1 to 10 inclusive which are pre¬ 
sented in Table I indicate that the “boiled” and “cold-stirred” emulsions 
were about equally effective in controlling this scale insect. Moreover, 
differences in time intervals between successive applications produced no 
outstanding variation in control. The equated percentages of control are 
not included because the per cent normally dead in the composite check 
for the same period, viz, 5.9 per cent as shown in Experiment 11, was too 
low to reduce the control results materially. Experiments 1 and 6 repre¬ 
sent the probable degree of control resulting from one application of the 
emulsion. The lower per cent of control obtained from similar treat¬ 
ments in Experiments 2 and 7 is explained by the fact that some of the 
observations were made before sufficient time had elapsed to allow all 
scales affected by the treatment to succumb. Two treatments at inter¬ 
vals of 11 and 26 days respectively as shown in experiments 3 and 8, and 
4 and 9, gave very good control. Three treatments with intervals of 11 
and 15 days between successive applications gave 100% control in 
Experiments in 5 and 10. 
These preliminary tests gave such convincing evidence of the insec¬ 
ticidal action of the emulsions that it was deemed desirable to establish 
the usefulness of the “boiled” emulsion by further experiments under 
normal growing conditions. Such tests would not only furnish additional 
proof of its insecticidal efficiency but also throw more light on its effect 
on the plants. 
Fortunately in 1923 a rather heavy infestation of Florida red scale, 
which was discovered in a house of palms at the Botanic Gardens, was 
Wothers, W. W. “Spraying for the control of insects and mites attacking citrus 
trees in Florida.” U. S. Dept. Agr. Farmers’ Bui. 933. 
