INSECT INJURIES 



93 



on them, and to devote land in which galls have 

 been fonnd to some annual crop for three or four 



years, until the 

 germs of the dis- 

 ease may be sup- 



93. Box for protecting plants 

 from insects. 



Protecting from 

 cut- worms. 



posed to be eliminated. These galls are common 

 upon woody plants, especially raspberries and 

 blackberries and the fruit trees. 



Of obvious insect injuries, there are two general 

 types, those wrought by insects which bite or 

 chew their food, as the ordinary beetles and 

 worms, and those wrought by insects which punc- 

 ture the surface of the plant and derive their food 

 by suction, as scale-insects and plant-lice. The 

 canker-worm (Fig. 92) is a notable example of 

 the former class, and all these insects are readily 

 dispatched by the application of poison to the 

 foliage. It is apparent, however, that insects 

 which suck the juice of the plant are not poisoned 



