The caterpillar is green with whiter ring divisions; a few long whitish
hairs on each segment; a faintly darker line along the back, and a paler
interrupted line along the sides. Head yellowish green marked with brownish
and sparsely clothed with whitish hairs. It feeds in June and July on the
leaves of oak and sometimes on sallow. It spins a whitish boat-shaped
cocoon on the under side of an oak leaf or twig, and therein turns to a
pale green chrysalis with a broad purple brown stripe along the back from
the head; the blunt last ring is tinged with purplish brown and the edge of
the ring immediately before it is fringed with minute hooks (Plate 72,
Figs. 4, 4a).
The moth seems to be out from August to April. It may be {148} beaten from
trees and bushes throughout the autumn, and during the later months of the
year it seems to hide in yews and hollies. Just before dusk it becomes
active and may then be netted as it flies; later on it may be seen regaling
itself on overripe blackberries, or on the ivy blossom, and it is not an
infrequent visitor to the sugar patch.
The species has been found in almost every part of England and Wales
wherever there are oak woods. In Scotland it occurs up to Argyllshire and
Moray. For Ireland, Kane gives Tyrone, Westmeath, Galway, Kerry, and
Limerick.
Distribution abroad: Central and Southern Europe, extending northwards to
Scandinavia, and eastwards to Amurland and Japan.