166 The Spraying of Plants. 



destroying plant lice. Quassia chips are worth from six to ten 

 cents per pound. 



QUASSIA CHIPS AND WHALE-OIL SOAP. 



Quassia chips 8 pounds. 



Whale-oil soap 7 " 



Water 100 gallons. 



" Soak the chips twelve hours in 8 gallons of water, or if hot 

 water is used, less time will be required. Dissolve the soap 

 by boiling in sufficient water to cover it ; strain the extracts 

 from the quassia and add the two ingredients together. Stir 

 thoroughly and dilute to make 100 gallons. 



"This solution is used successfully among the hop growers 

 for exterminating hop lice in the large fields. It is not injurious 

 to foliage. . . . For some species of aphis [upon other plants] 

 a stronger solution may have to be used, and in such cases dilute 

 only to 80 gallons instead of 100." * 



QUICKLIME. See LIME. 



RESIN SOAP. 



Resin 2 pounds. 



Caustic soda 1 pound. 



Tallow 1 " 



Dissolve the caustic soda in 1^ gallons of water. In this, 

 dissolve the resin and tallow with moderate heat, adding water 

 to make 22 pints of brown, thick soap. For use dilute with 

 44 gallons of water and apply as a spray. It is used as a sum- 

 mer wash to destroy insects. 



RESIN WASHES. The history of these washes has been dis- 

 cussed on page 85. Their action is of two kinds. Some insects 

 are killed when these washes come in contact with their bodies, 

 an action similar to that of the kerosene emulsions. But scale 

 insects are often so well protected that they cannot be directly 

 reached by the applications. The action of the resin washes is 

 then to form a covering over the insect so that both air and 

 moisture will be excluded. In this manner the pest is literally 

 smothered to death. These washes are particularly valuable in 

 destroying scale insects. In the East, where such insects are less 

 troublesome, kerosene emulsion is more commonly recommended, 



* Washington State Board of Sort. 3d Biennial Sept. 1893-94, 71. 



