BORERS 



273 



ficult to detect on the branches unless badly infected. The 

 tiny yellow body is completely covered with a single small 

 dark scale not so large as the head of a pin. The dead 

 scales are gray in color. When rubbed off they leave 

 white circular spots, and cause badly infected branches to 

 have a rather grayish appearance. This scale multiplies 

 very rapidly and with its 

 tube-like mouth parts it 

 pierces the surface of the 

 plant, sucking the juices 

 within. If not controlled, 

 it will kill large fruit trees 

 in a few years. 



In infected regions, trees 

 must be sprayed each 

 year. The application of 

 strong lime-sulphur spray 

 applied early in the spring 

 just before the buds open is 

 now the standard method 

 of control. It is necessary 

 to spray the trees while 

 they are dormant to per- 

 mit the application of a 

 spray strong enough to 

 kill the insect without injuring the trees. As this is a 

 contact poison, thoroughness is of prime importance, for 

 a small number of insects left untouched will cause serious 

 infection the following season. 



Borers. Borers are injurious to peach and apple trees. 

 They usually infect the trunks of the trees just above the 

 ground. They cannot be controlled by spraying, as the 



M. AND H. PLANT PROD. 1 8 



Fig. 147. San Jose scale insects. Enlarged. 

 m, male scale ; f, female scale ; y, young 

 scale ; a, young insect. 



