FOES AND FRIENDS OF THE PLANT 215 



snow-white color makes it easy to recognize. The young in- 

 sects may be known by the fact that they are smaller than 

 any similar scale insect and confine themselves to the under- 

 side of the leaf. 



The best way to prevent it from spreading is to remove all 

 the infested leaves and burn them at once. When it once 

 gets in, it must be dealt with like any scale insect. (California 



Experiment Station, Circular 30.) 



v 



SCALE INSECTS 



The scale insects (figures 123 and 124) are not larger 

 than plant lice and, like them, feed by sucking the juices 

 of the plant through their beaks. 



Some are covered with a shell of wax, like the San 

 Jose and oyster-shell scale. Some have a waxy cover- 

 ing, but no true shell. Others have no waxy covering 

 and are called naked scales, such as the brown scale 

 of the apricot and the black scale of the olive. 



The males have wings, but no mouth parts. The 

 females have mouth parts, but no wings. The females 

 of many kinds lose their legs early in life and remain 

 motionless thereafter. 



Scale insects may be entirely controlled by sprays, 

 which should be applied with considerable force. (Cali- 

 fornia Experiment Station, Bulletin 166.) 



San Jose scale. The appearance of this common and in- 

 jurious scale is familiar to every one. The insects pass the 

 winter in a half-grown condition. In the spring they grow 



