Only the males have orange tipped wings. Females' wings are white, tipped with black. The undersides of the hindwings of both sexes have a mottled green effect, making it easy to distinguish a female from the other "whites".
Wingspan 40 - 52mm.
Single brooded, overwintering as pupa.
Males emerge about a week before females. May be seen on the wing from mid April to June.
A major expansion in range occurred 25 - 30 years ago, spreading westwards from Moray and Speyside, now as far as Skye, Arisaig and Knoydart, and northwards to Sutherland. A postcard survey conducted in Spring 2007 may reveal further expansion.