442 



THE MONTHLY BULLETIN. 



ance of the younger trees was noticed in the case of the older. This 

 appearance cannot be described better than to liken it to that of grape 

 vines with an infestation of Phylloxera. While the damage to pears 

 from woolly aphis is not usually as great as that to grape vines from 

 Phylloxera, the habits of growth of affected trees are somewhat similar 





/5H 







Fig. 94. — Healthy growth of young 

 Bartlett pear the first season. 

 Roots free from the woolly 

 aphis. (Original.) 



to that of the affected vines. In other words, there is a cabbage head 

 appearance due to the serious checking of the growth, and in the case 

 of the pear there is an early dropping of the foliage in the fall, which 

 seems to be associated with woolly aphis trouble. 



FIBROUS ROOTS SUFFER MOST. 



The characteristic galls of the woolly aphis on apple trees are 

 familiar to practically everyone who has made observations in an apple 

 orchard. Nothing of this kind has ever been observed on pears. On 

 the apple very large roots may be infested. On the pear the attack is 

 confined almost entirely to the very small roots and seldom has a colony 

 of the aphids been found where roots were of greater diameter than 

 that of a lead pencil. The extremely fine network of roots which per- 

 meates the soil throughout the entire area of an orchard is affected and 

 apparently to as great a degree midway between two rows as close by 

 the trees. Small clods which on the surface show no indication of the 

 aphis may upon being broken open, be found to contain a score of 



