142 Control of Parasites 



For the ap])Iication 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 dissohed in one gallon of boiling water, 

 and is immediately added, boihng 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 larvje, 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 \\\i\\ 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 di^'ided 

 ;\ 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. 



1 A number of trees were killed in Ithaca in 1903 by foolishly applying 

 pure kerosene to the bark with the erroneous notion of benefiting them. 



