Insects Injurious to the Apple. 



145 



and Mr. Charles Loimsbury state to be a fact, but which fruit-orowers 

 of very great skill have proved to be the case in Australia, New 

 Zealand and South Africa. 



The mere presence on the trunk and boughs is nothing as long as 

 we can prevent its occurrence below ground. 



The damage caused by the Woolly Aphis is particularly severe 

 to young stock, but old trees also suffer in two ways. First, the 

 aphides lessen the vitality of the tree by constantly 

 sucking out the sap ; secondly, by the wounds 

 caused by their punctures on young wood, they 

 cause an abnormal growth of soft tissue, which 

 forms rounded swellings, so very characteristic 

 of Woolly Aphis presence (Fig. 119). These 

 swellings split later on, and from them arise those 

 large rugose deformities, so often put down to 

 " canker." At the same time they cause similar 

 damage on the roots, but the swollen gall-like 

 growths that they produce do not necessarily 

 split in the way we find above ground (Fig. 

 118). In these two ways the life of the 

 tree is gradually sapped, and not infrequently 

 young trees die under this rough usage. In 

 any case stunted deformed trees result, and 

 but scanty and poor quality fruit is borne by 

 the trees. 



But there is a third way, I feel certain, in 

 which this AVoolly Aphis works injuriously. 

 After keeping records during the past twenty 

 years, I find that in nearly all cases trees infested 

 with canker have or have had Woolly Aphis 

 attacking them. During the summer of 1903 

 two trees (Worcester Pearmain and a Russet), 

 which were perfectly clean, were infected with 

 Woolly Aphis ; next year both were attacked by 

 canker. One tree close to them not attacked by the Schizoneura is 

 still clean. 



There is no doubt that indirectly this aphis, by causing wounds 

 of greater extent than any other species on the apple, predisposes the 

 trees to the fungus enemy, for which we have no known remedy. 



The importance of knowing the life-history is therefore very great, 

 for it is only by so doing that we can learn how% when and where to 

 apply any satisfactory treatment. 



[F. E. 

 FIG. 119.— EARLY STAGE 

 OF ATTACK OF WOOLLY 

 APHIS ON YOUNG -WOOD. 



