278 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



before the winged generation appears, with some substance 

 which will destroy them, the pest may be prevented from getting 

 a start the next season. Spraying the trees during the fall is 

 best, because a stronger or more caustic solution can then be 

 applied without danger of injury to the tree. A winter wash of 1 

 pound of concentrated lye to 2 gallons of water may be used as a 

 spray to advantage in killing a large share of the eggs, but should 

 not be applied after the buds commence to swell in the spring. To 



\ 



FIG. 205. The hop plant-louse, male enlarged. (After Riley, U. S. D. Agr.) 



lessen the number of eggs all wild plum-trees in the neighboring 

 woods should be destroyed. As soon as the crop is harvested, 

 the hop-vines should be burned or thoroughly sprayed with 

 kerosene emulsion, so as to kill off the males before they have 

 been able to fertilize the females. 



For spraying the plum-trees and hop-vines kerosene emulsion 

 has been found very satisfactory, diluting the stock solution with 

 15 parts of water. 



Fish-oil or whale-oil soap used at the rate of 1 pound to 8 

 gallons of water will prove an effective spray against the lice. 

 Also see page 664. 



