844 



THE FKUIT INDUSTRY ix XEW YORK STATE 



This pest occurs on a large number of trees and shrubs, dis- 

 playing a marked preference for the peach, the Japanese quince, 

 and certain varieties of apple, especially Ben Davis and Greening. 



Several natural enemies prey 011 the San Jose scale, notably a 

 small, black lady beetle, SimiUa miseUa Lee., and some extremely 

 minute and recently discovered four-wirged parasites, especially 

 Prospaltella perniciosi Tower. The presence of the latter is most 

 easily recognized by the irregular, circular holes made by the 

 insects as they escape through the protecting scale. These para- 

 sites may destroy a considerable percentage of the pests, al- 

 though present conditions do not justify relying to any great ex- 

 tent on their good offices. 



FIG. 231. COMMON SCALE INSECTS: (A) 

 APPLE TREE BARK LOUSE; (B) SCURFY 

 BARK LOUSE; (c) FEMALE, AND (D) 

 MALE SAN JOSE SCALE. 



The most satisfactory method of controlling the San Jose 

 scale is by thorough applications of a lime-sulphur wash diluted 

 to about 4.5 degrees Baume and applied during the dormant 

 season, preferably late in the spring just before the buds start, 

 or, under certain conditions, prior to the showing of the pink in 

 the blossom buds. This very late spraying is advisable only when 

 there is an infestation by led bugs, and it is desired to destroy 

 the young of these pests when spraying for scale. A delayed 

 treatment of this character, to which nicotine is added, is very 

 serviceable in checking the latter and plant lice as well as red 

 bugs. 



OYSTER-SHELL SCALE AND SCURFY SCALE 



There are two common, occasionally abundant, scale insects, 

 one of which is the oyster-shell scale, Lepidosaphes ulmi Linn., a 



