Early fall, several of these small/medium-sized caterpillars crawling around the dry rocky edges of a mountain stream. I might've collected one had I been able to determine the vegetation whence they came or where they were headed, but I couldn't find any others, nor any pupae, in the surrounding vegetation (Red Alder, Sycamore, Salix sp, Big-leaf Maple, French Broom). Looked at a LOT of pages of larvae on BG -- no match.

Also: presumably the adults would have been flying some weeks previously, no? Buckeyes and Lorquin's Admirals are abundant in this locale throughout spring and summer, but Junonia and Vanessa caterpillars on BG have stubby black spines, not fine white ones like these. Anyone?