The antennae of the female are pectinated, but the teeth are shorter than those of the male; and the blackish streak on the wings are usually less defined.

— The form from Lapland, lapponica Teich, is uniformly dark grey-brown, the light median band of the hindwing absent.

— A like-wise dark form is known from the Black Sea and Southern Siberia, being presumably more widely distributed in Central Asia; this is pontica Stgr.

Larva light bluish green, with 6 rows of raised white dots, 4 being dorsal and 2 lateral.

Above the spiracles a white longitudinal stripe which is anteriorly thinly edged with fuscous, at the prothoracical stigma a red streak.

The pencilling of the wings, which are held in steep roof-shape, render the specimen exactly similar to a splinter of wood, of which the palpi represent the split end, the resemblance being especially striking in a pair in copula.