This a relatively long-lived butterfly. One of its host plants is willow. The caterpillars are gregarious and are found in abundance on the same branch.
This was reared from a caterpillar. The butterfly is about to eclose from the chrysalis. The brown one is empty.
OLYMPUS IMAGING CORP. E-520, f/6.3 @ 300 mm, 1/250, ISO 400, No Flash
