44 the: COI.ORADO EXPERIMENT STATION 
the species from tree to tree. The earlier this is done after the 
lice first appear the better, for then they are nearly all accumulated 
upon a few sprouts or limbs near the ground. 
PREPARATION OF THE INSECTICIDES MENTIONED 
IN THIS BULLETIN. 
KEROSENE EMULSIONS 
The standard formula for mixing the stock solution of kero¬ 
sene emulsion is as follows: 
Water i gallon. 
Tak-a-Nap, Whale-oil, or Laundry soap 1-2 pound. 
Kerosene, 2 gallons. 
For use, dilute with water to secure the desired percentage of 
oil. 
For example, if a spray containing 5 per cent oil is desired, 
i^se 3 3-4 gallons of the stock solution, and dilute with water to 
make 50 gallons of spray. If a 6 per cent spray is desired, use4 1-2 
gallons of the stock solution to make 50 gallons of spray, or if a 7 
per cent spray is desired, use 51-4 gallons of the stock solution in 
making up 50 gallons, or practically i part stock solution to 9 
parts of water. This last named strength is the one most commonly 
used for the destruction of plant lice upon plants while they are in 
foliage. Larger amounts of the stock solution may be prepared 
using the same ratio. If a stronger spray is to be used than those 
given above, it is only necessary to dilute with a smaller propor¬ 
tion of water, bearing in mind in computing the percentage of oil 
in the spray that the stock solution is two-thirds oil. 
The necessary steps are: Dissolve 1-2 pound soap in i gallon 
boiling water. While boiling hot add this to 2 gallons kerosene 
and briskly agitate for about five minutes. A creamy mixture will 
be formed which, when diluted with water, will mix readily with¬ 
out allowing free kerosene to rise to the top. After agitating, add 
a small quantity of the stock solution to a bucket of clear water 
for trial. It should mix completely through the water, like milk. 
If it rises to the top as free oil, the stock solution will have to be 
heated again to boiling and churned until it will stand this test. To 
avoid accidents, the boiling solutions should be removed from the 
fire when it is mixed with the kerosene. An emulsion can be formed 
with greater ease if the oil is also warmed, but the heating of kero¬ 
sene over a live fire, for safety, should only be attempted out of 
doors and away from all buildings. The mixture must be watched 
closely also to prevent its boiling over the sides of the vessel and 
igniting. 
Mixing the emulsion is not a difficult operation. It can be 
done by any orchardist. The essentials of success are in having 
the soap suds hailing hot when the solutin is added to the kerosene, in 
