THEIR RELATION TO PLANTS 



73 



frequently cause the death of the plants attacked; 

 but there are others, like those attacking the trunks 

 and branches of oak and maple, that may infest their 

 host for years without causing obvious harm. Not 

 only the tissue above ground is attacked, for one species 



Fig. 29. — The peach bor 



'sa; male above, female below. 



at least occurs on the roots of grape, and others are 

 underground on oak. 



The Cossids are much larger forms and correspond- 

 ingly more dangerous. The European Zeiizera pyrina 

 or wood-leopard moth, which has been introduced 

 into the eastern United States, frequently girdles 

 young trees and often weakens the branches of older 

 ones to such an extent as to make them easy victims 



