142 Control of Parasites 
For the application of any of these mixtures a bright, 
sunny day should be chosen, and the trees should be dry. 
The spraying should just wet the plant without allowing 
the liquid to run down the trunk. 
The kerosene emulsion is the standard mixture for this 
class of insects. Half a pound of whale-oil soap, or other 
soap, is grated and dissolved in one gallon of boiling water, 
and is immediately added, boiling hot, to two gallons of 
kerosene, pouring in slowly, and the mixture thoroughly 
agitated for ten to fifteen minutes, until the consistency of 
cream (with an increase of one-third to one-half in bulk) is 
attained. This is a stock solution, which will keep indefi- 
nitely, and in using must be diluted, adding from fifteen to 
twenty parts of water for soft-bodied insects, and seven to 
nine parts of water for hard-bodied larve, beetles, and 
insects. 
There is some danger in the kerosene emulsion, if not 
properly made and if carelessly used, for the kerosene 
flowing down the trunk and collecting about the roots 
may interfere with their aeration and may even produce 
death." 
The whale-oil soap by itself, or any good soap, is effective 
on soft-bodied insects and scales. The soap should be made 
of caustic potash rather than soda, as this is more effective 
and sprays more easily. A pound of soap finely divided 
and dissolved in three to six gallons of hot water is about 
the right strength. 
A decoction of tobacco (one pound of tobacco stems to 
one gallon of water, steeped for two or three hours and 
strained) is also effective, and can be used without danger, 
like the soaps. 
1A number of trees were killed in Ithaca in 1903 by foolishly applyng 
pure kerosene to the bark with the erroneous notion of benefiting them 
