Staudinger an extraordinary aberration with both wings broadly fuscous margined and the basal part of the forewing brownish.

Perhaps accidental, as the yellow of this species is highly susceptible to various kinds of chemical action.- provincialis Ob.

The larva is brown or green with a "horn" on its back and feeds on a variety of trees and shrubs.

Recorded food plants include apple, birch, blackthorn, currant, hawthorn, Prunus, rowan, Amelanchier and willow.

The species, due to its complex life cycle, overwinters either as a larva or a pupa.

The English zoologist Edward Bagnall Poulton, author of The Colours of Animals (1890) described countershading in insects including the caterpillar larvae of the brimstone moth.

[2] The American artist Abbott Handerson Thayer, generally considered the originator of the theory of countershading, credited Poulton with its partial discovery.