24 
THE WOOLLY APPLE APHIS. 
(Schizoncura lanigera Hausmann—figs. 14 and 15.) 
One often notices on the trunk or larger branches of the apple 
Fie. 14.—Schizoneura lanigera; a, agamic female; b, 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 
Fig, 15,—Schizonewra lanigera; a, b, work on confined to the apple, but there are 
Rede ce Verte afew varieties, such as the Northern 
Spy, that appear to be immune against its attacks. The lice com- 
en 
