24 



THE WOOLLY APPLE APHIS. 

 (Schizonmra lanigera Hausmann— figs. 14 and 15.) 

 One often notices on the trunk or larger branches of the apple 



^^^^,:ijia33»i??SSSSiBaSS^^ 



Fig. 14. — SehisoTieura lamgera; a, agamic female; 6, larva; c, pupa; d, winged female. (Marlatt.) 



small, bluish-white, flocculent patches of a woolly substance, which 



indicate the presence of this insect. 

 This cottony substance is a wax-like 

 excretion clinging to the posterior 

 parts of a small, reddish-brown 

 wingless aphis. It is not, however, 

 this form on the trunks that causes 

 injury. This aerial form is but the 

 indication that there are other speci- 

 mens, under the ground and feeding 

 on the roots of the tree. It is the 

 latter form that seriously affects the 

 vitality of the tree. Upon the trunk 

 the lice often cause a roughening 

 of the bark, especially on the new 

 growth around scars made by prun- 

 ing. On the roots the lice cause 

 hard and large knots, which eventu- 

 ally produce a "club-footed" con- 

 dition of the roots. Such trees 

 usually' show their weakness by the 

 fewer and duller colored leaves. 



The woolly aphis is practically 

 confined to the apple, but there are 

 a few varieties, such as the Northern 



Spy, that appear to be immune against its attacks. The lice com- 



FiG. 15. — Sehizoneura lanigera; a, 6, work on 

 roots; €, a Ioiiho. ( .Marlatt, ) 



