Plants as Affected by Animal Parasites. 155 
b — Dissolve one-fourth pound of good, hard soap in two 
quarts of boiling water, and add at once one pint of 
kerosene. Agitate or pump, as above directed. For use, 
dilute with twice its volume of water; or 
c— Dissolve one-half pound of hard soap in one gallon 
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 spraving nozzle. About ten per cent. of kerosene 
should be used for most plants (317). 
295. Caustic Potash, in solution, is useful for des- 
troying certain scale insects, as the oyster-shell bark-louse,* 
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 dor- 
mant and growing trees. The resin is sometimes saponified 
with caustic soda and simply diluted with water; fish oil, 
or petroleum may also be added. The following and other 
formulas are in use: 
a— Dissolve one pound of caustic soda in one gallon of 
water in a covered iron kettle. Pour out half of the solu- 
tion, and to the remainder add 8 pounds of resin, and boil 
until dissolved. Then pour in very slowly the rest of the 
caustic soda solution, and boil the whole, stirring it con- 
stantly until it will unite with water, forming a liquid 
* Mitilaspis pomorum. 
