Epping, Rockingham County, New Hampshire, USA May 15, 2013
I discovered this caterpillar on a quaking aspen (Populus tremuloides) sapling, eating the leaves. After trying to ID the larva and reading the notes on BugGuide for Limenitis sp. figured I would have more success with ID if I tried to rear it.
About 15 days after pupating, a beautiful red-spotted purple butterfly emerged!