257 



could be safely applied, which would at another time pro^^e 

 injurious. 



Pro. Riley writes (5th Report U. S. Ent. Com., p. 37) re- 

 garding the Resin washes : — 



" Mr. Koebele had good success with the resin compound 

 prepared as follows : Dissolve 3 pounds of sal-soda and 4 pounds 

 of resin in three pints of water above fire ; when jDroperly dis- 

 solved, add water slowly, while boiling, to make 36 pints of com- 

 pound. A very strong solution of this was used on pear trees 

 without injury to the foliage, the solution consisting of 3 pints of 

 the compound to 4 of water. Numerous successful expei'iments 

 were made with one part of the compound and 8 parts of water, 

 and this strength for most purposes will be sufficient. 



" Mr. Coquillett has found the following to be an excellent 

 formula for the preparation of this compound — 



Caustic soda ... ... ... 1 jDound 



Resin ... ... ... 8 pounds. 



Water to make ... ... ... 32 gallons. 



" Dissolve by boiling the caustic soda in a gallon of water ; 

 add the i^esin to one half the soda solution and dissolve it by 

 boiling ; add the remainder of the soda solution and boil over a 

 hot fire, stirring constantl}'. When sufficiently cooked it will 

 assimilate with water like milk, which it much resembles. Add 

 water and strain through a fine sieve. 



" An emulsion of kerosine with resin compound was satis- 

 factorily accomplished by taking equal parts of both substances 

 and working them together for two minutes with a pump. The 

 emulsion is not so stable as the emulsion with soap, but it is 

 eminently effective against scale-insects and aphides. At my 

 suggestion the addition of arsenic in the pi'oportion of 1 pound to 

 from 75 to 300 gallons of the resin, or resin and kerosine wash, 

 was made, and this addition was found to greatly increase the 

 efficiency of these insecticides." 



Mr. Coquillett's resin wash has been vi.sed on Orange and 

 Lemon trees without causing any injury to foliage or fruit. It 

 proves fatal to a large proportion of the black scales, ( Bernardia 

 oleoej, but probably some always survive, making it expedient 

 to apply the -remedy more than once. The black scale, however, 

 seems exceptionally hard to exterminate, being well-protected by 

 its structure and very prolific, and the kerosine emulsion is also 

 reported to have failed to destroy it. Mr. Ellwood Cooper, of 

 Santa Barbara, California, applies the kerosine emulsion hot 

 (140°) against the black scale and considers it the best remedy. 



The kerosine emulsion is the most convenient for use, but it 

 is found that the resin wash is cheaper. One difficulty with the 



