INJURING THE BRANCHES. 35 



The Woolly Aphis. 



Schizoneura lanigera. 



There are frequently found on the limbs and 

 trunks of young apple trees, masses of a white, woolly 

 substance, similar to that occurring on the limbs of 

 maple trees infested by the Maple Bark-louse. If 

 one of these masses be examined there is found be- 

 neath it one or more small, yellowish plant-lice. 

 This is the insect that has for a long time been pop- 

 ularly known as the Woolly Aphis. There are two 

 forms of the insect, one attacking the roots, the pres- 

 ence of which may be easily detected by the knotty 

 appearance of the infested rootlets, and one attacking 

 the limbs and trunk. Like other aphides, these in- 

 sects multiply rapidly during the summer months, 

 by giving birth to living young. Most of these sum- 

 mer forms are wingless, but occasionally winged 

 ones are found. They all injure the tree by sucking- 

 out its sap through their tiny beaks. They are es- 

 pecially liable to infest young trees, or those which 

 are unhealthy. The woolly matter which they se- 

 crete as a covering serves to protect them from the 

 damp earth, in their subterranean home on the roots, 

 and probably is a partial protection from enemies 

 above ground. It is not a complete protection, how- 

 ever, as they are preyed upon by a small, parasitic 

 fly and by lady-bird beetles and their larva'. 



