The female of this species is wingless and rather spider-like and can be found on the trunks and stems of its larval food plants.

There are two dark brown oblong spots in the upper half of the terminal area.

As with the peppered moth, the darker forms tend to be prevalent in industrial areas.

The egg is oval with very shallow, somewhat zigzag longitudinal ridges, a cell-pattern only discernible on high magnification and brownish yellow, without gloss.

It feeds on a wide variety of trees and shrubs (see list below) and can be a serious pest in orchards.