Z2)^ AGRICUI.TURE OF MAINE. 



3. WooLivY Aphis of the Apple. 

 {Schizoneura lanigera Hausmann.) 



Throughout the summer on the lower portion of the trunk 

 and particularly on the water sprouts of the apple may often 

 be seen small bluish-white flocculent or cottony patches, which 

 indicate the presence of colonies of one of the worst enemies of 

 the apple, viz., the insect known as woolly aphis (fig. 34). 



It exists in two forms, the one just referred to, above ground 

 on the trunk or water shoots, and another inhabiting the roots. 

 On the roots its attacks induce enlargements or galls or swell- 

 ings, and in the cracks of these galls and swellings the root 

 form occurs in clustered masses. The injury 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. 



The damage is particularly serious in the case of nursery 

 stock and young trees and is less often important 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 growth of 

 hard fibrous enlargements (fig. 35) with the results in a year 

 or two of the dying of the rootlets and their ultimate decompo- 

 sition with attendant disappearance of the galls and also of the 

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

 i'.- often obscure. On the trunks the presence of the lice some- 

 times results in the roughening 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 

 greener side of the stems. The damage above ground, though 

 commonly -insignificant, is useful as an indication of the prob- 

 able existence of the lice on the roots. A badly attacked tree 

 assumes a sickly appearance and does not make satisfactory 

 growth, and the leaves become dull and yellowish, and even if 

 not killed outright it is so weakened that it becomes especially 

 subject to the attacks of borers and other insect enemies. 



The common forms both on the roots and above ground are 

 wingless lice, not exceeding one-tenth of an inch in length, and 



