168 Principles of Plant Culture. 



liflower and turnip, to prevent their destruction by the 

 flea beetle.* 



294. Kerosene is a very useful insecticide for a class 

 of insects not readily destroyed by other means (316). 

 It has generally been used as an emulsion made with 

 soap and water, for which the following formulas are 

 good. 



a Dissolve one quart of soft soap, or one-fourth 

 pound of good hard soap, in two quarts of boiling 

 water; remove from the fire, and pour into a can con- 

 taining one pint of kerosene. Agitate violently in the 

 can for three minutes. For use, dilute with an equal 

 quantity of water; or 



b Dissolve one-half pound of hard soap in one gal- 

 lon of boiling soft water; add at once two gallons of 

 kerosene, and churn or otherwise violently agitate for 

 five or ten minutes. For use, dilute with 15 parts of 

 soft water. 



Kerosene may also be applied in intimate mixture 

 with water, secured by pumping both liquids at once 

 through a good spraying nozzle (Fig. 70). About ten 

 per cent, of kercsene should be used for most plants. 



295. Caustic Potash in solution is useful for destroy- 

 ing certain scale insects, as the oyster-shell bark-louse,v 

 for which solutions of one-fourth pound to the gallon 

 of water may be applied during winter. 



296. Resin (or rosin) Washes are valued for destroy- 

 ing various scale insects in southern and western United 

 States. They are adapted with modifications to both 

 dormant and growing trees. The resin is sometimes 



*Phyllotreia vittala. ^ Mytilaspis pomorum. 



