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. She is white or yellow-and-black patched. The male is fully winged (wingspan 40–45 mm) and very variable. The ground colour of the forewing is pale yellow or light yellow ochre and suffused dark grey. The basal and distal fasciae are dark brown. The basal fascia is bordered on the inner side by a brown cloud; the distal fascia has a brown cloud on the outer edge. There is also a brown cloud along the costa. There are two dark brown oblong spots in the upper half of the terminal area. The hindwing is grey white with grey suffusion. There is a grey-black discal spot on both wings. There are numerous and significant deviations from this colour pattern and some specimens are very dark. See Prout (1912–16) [1] Truly melanic forms are also frequent. As with the peppered moth, the darker forms tend to be prevalent in industrial areas.
The adults have been recorded from September to December in the Great Britain and Ireland. Males are attracted to light.
The egg is oval with very shallow, somewhat zigzag longitudinal ridges, a cell-pattern only discernible on high magnification and brownish yellow, without gloss.
The larva is also variable from cream to dark brown and quite gaily coloured. It feeds on a wide variety of trees and shrubs (see list below) and can be a serious pestinorchards. The species overwinters as an egg.
^Prout, L. B. (1912–16). Geometridae. In A. Seitz (ed.) The Macrolepidoptera of the World. The Palaearctic Geometridae, 4. 479 pp. Alfred Kernen, Stuttgart.pdf
^Waring, Paul; Townsend, Martin; Lewington, Richard (2003). Field Guide to the Moths of Great Britain and Ireland. Rotherwick: British Wildlife Publishing. p. 174. ISBN0 9531399 2 1.
Chinery, Michael (1991). Collins Guide to the Insects of Britain and Western Europe.
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