238 MAINE AGRI CULTURAL EXPERIMENT STATION. IQI2. 



malformations the root form occurs in clustered masses. The in- 

 jury to the trees is due both to the sucking up and exhaustion of 

 the vital plant juices and to the poisoning of the parts attacked, 

 as indicated by the consequent abnormal growths. Fig. 430. 



The damage is 

 particularly seri- 

 ous in the case of 

 nursery stock and 

 young trees and is 

 less often impor- 

 tant after the tree 

 has once become 

 well established 

 and of some size. 

 Where this insect 

 is abundant all 

 the roots of a 

 young tree to the 

 depth of a foot or 

 so become clubbed 

 and knotted by 

 the gowth of hard 

 fi b r o u s enlarge- 

 ments with the 

 results in a year 

 or two of the dy- 

 ing of the rootlets 

 and their ultimate 

 decomposition with 



Fig. 439. Crown and root of young apple 

 tree, showing characteristic swellings or 

 galls produced by the root lice. (From 

 Alwocd.) 



attendant disappearance of the galls and 

 also of the lice, so that after this stage is reached the cause of 

 the injury is often obscure. 



On the trunks the presence of the lice results in the roughen- 

 ing of the bark or a granulated condition which is particularly 

 noticeable about the collar and at the forks of branches or on 

 the fresh growth around the scars caused by pruning, which 

 latter is a favorite location. On the water shoots, they collect 

 particularly in the axils of the leaves, often eventually causing 

 them to fall, and on the tender growth of the stems. The 

 damage above ground, though commonly insignificant, is useful 



