White-spotted Satyr

This butterfly is a deep shade species and flies at dusk, as well as around lights at night like a moth. It is large and cryptically colored on the hind wings for landing on tree trunks in dark places. It blends really well with bark-moss-lichen mixtures. This butterfly tends to cluster in large numbers during the day in deep shade (see this spotting for top views and clustering behavior:
http://www.projectnoah.org/spottings/123316081/fullscreen).
Family Satyridae.