THE INSECT WORLD. 



133 



Fig 



Woolly apple-louse, Schizoneura lanigera: show- 

 ing a group of specimens on bark, a crevice on a 

 branch, in which they congregate, and a winged 

 form. 



"woolly plant-lice," belonging to the genus Schizoneura, These 

 cover themselves with a secretion resembling fine cottony fibre, 

 which conceals them more or less completely. Thus there may 

 appear to be tufts of cot- 

 ton attached to leaves 

 or twigs, beneath each 

 of which we find, how- 

 ever, a great mass of 

 plant lice busily en- 

 gaged in feeding. The 

 ' ' alder - blight' ' and 

 ' ' beech-blight' ' are due 

 to species of this kind, 

 and more important 

 than all is the ' ' apple- 

 blight," or " the woolly 

 apple-louse. ' ' This spe- 

 cies, Schizoneura lani- 

 gera^ has been intro- 

 duced into other countries, and is known in England and Aus- 

 tralia as the "American blight." Young trees are frequently 

 injured by these aphids, which gather in masses on the trunks, 

 and cause the death of the bark below the point of attack. The 

 eggs may be found 



singly in the bark 9^- 

 crevices during win- 

 ter, completely envel- 

 oped in the dry skin 

 of the female, and 

 from them appear, in 

 spring, agamic, wing- 

 less forms, which bear 

 living young. This 

 method of reproduc- 

 tion continues until the 

 winged type, which 

 spreads to other localities, is produced in late summer. The 

 sexed forms are wingless and mouthless, the female producing 

 only a single egg ; but in the southern parts of our country it 



Schizoneura lanigera, root form. — a, galls caused by 



them on apple-roots ; b, 

 winged form. 



wingless, wax-coated form ; c, 



