74 INSECTICIDES FOR SUCKING INSECTS 
water. Have the water boiling hot. As soon as the soap is all dis- 
solved, remove the solution from the fire and add 2 gallons of kero- 
sene. At once agitate the material violently. This is best accom- 
plished by the use of a bucket pump, turning the nozzle back into the 
bucket, so that the material is constantly passed through the pump. 
In a few minutes a smooth, creamy emulsion is formed, without any 
free oil. This will become thicker as it cools, but if it is properly made, 
no oil will separate out. This is the stock material, and will keep well, 
if sealed from air. 
For use on trees or shrubs that are dormant it is customary to dilute 
the stock emulsion with 5 to 7 parts of water. On trees or plants in 
leaf dilute with 10 to 15 parts of water, depending on the type of in- 
sect and the kind of foliage. Soft-bodied insects such as plant lice are 
easily killed by a dilution containing only 5 or 6 per cent of oil. 
To get exact dilutions use the following table: 
For 4% strength add 153 gallons of water to 1 gallon of stock solution- 
For 5% strength add 123 gallons of water to 1 gallon of stock solution. 
For 7% strength add 83 gallons of water to 1 gallon of stock solution. 
For 10% strength add 53 gallons of water to 1 gallon of stock solution. 
For 12% strength add 44 gallons of water to 1 gallon of stock solution. 
For 15% strength add 33 gallons of water to 1 gallon of stock solution. 
For 18% strength add 23 gallons of water to 1 gallon of stock solution. 
For 20% strength add 23 gallons of water to 1 gallon of stock solution. 
For 25% strength add 132 gallons of water to 1 gallon of stock solution. 
Oil sprays are best applied on a sunny day when the wind is blowing, 
since surplus oil will then evaporate more quickly and there will be less 
danger of injuring the plant. 
Crude oils are emulsified in the same way as kerosene. For certain 
insects, as indicated later, this spray is effective and desirable. 
Linseed Oil Emulsion 
Hard soap... é : ; ; . 1 pound 
Hot water (soft). ; F 4 . 1 gallon 
Linseed oil (raw). : : : . 2 gallons 
Dilute as directed. 
