DESTRUCTIVE INSECTS. 



169 



can be done also by spraying the trees several times during the 

 growing season with a kerosene-water pump, using about 20 

 per cent, of kerosene, or with whale-oil soap, about one pound 

 in four or five gallons of water. For a winter wash a solution 

 of good whale-oil soap, two pounds in one gallon of water, has 

 been found very effectual. Pure kerosene is also effective, 

 but often injures the tree. Crude petroleum applied as a 

 winter wash, in a 25 to 4o-per-cent. 

 mixture, with a kerosene - water 

 pump, is also proving a valuable 

 addition to the insecticidal batter- 

 ies that may be directed against 

 this pest. Very effective work has 

 also been done in the East with the 

 California wash of lime, sulphur, 

 and salt. 



Fumigation with hydrocyanic 

 acid gas is the most perfect method 

 of controlling the San Jose scale, 

 but it requires expensive appa- 

 ratus for orchard work. Nursery 

 stock, however, can be cheaply 

 fumigated, and when properly 

 done, it will prove a great safe- 

 guard to the fruit-grower against, not only this scale, but 

 many other injurious insects often sent out by nurserymen. 



Lecanium Scales. These are large, soft-shelled, brown scales 

 about the size and shape of a half pea. There are many 

 species, some of which, like the Black Scale of California, are 

 very destructive. A few years ago one of these Lecaniums 

 appeared in overwhelming numbers in several plum orchards 

 in western New York, and many bearing trees were killed. 

 Climatic conditions and its insect enemies, however, soon 

 turned the tide, and the pest may remain in its former obscur- 

 ity for many years. 



Such scales can often be successfully controlled by spray- 

 ing the trees when dormant with kerosene emulsion, one part 

 to four of water; doubtless a kerosene-water pump, using 20 or 

 30 per cent, of kerosene, or whale-oil soap, one pound in two 

 to four gallons of water, would prove equally effectual. 



FIG. 230. The Peach Lecanium 

 Scale, natural size and en- 

 larged. 



