Uncommon and rather poorly-known in California, this is a species of cool, moist forest - often seen along muddy streamsides, sitting with wings fully expanded. It ranges from the upper foothills to mid-elevation (roughly 1500 to 6000' at the latitude of I-80). The only other small Dusky-Wing with a "chain-dotted" forewing pattern is the larger, serpentine-endemic Sleepy Dusky-Wing, E. brizo lacustra. Note the squarish, "cut-off" forewing shape of E. icelus!
One brood in late spring (April-June). Host plant willow (Salix), but life-history not well studied in California. This species extends all the way to the Atlantic Coast and may be a relict in our fauna. In the Bay Area it is recorded (oddly) only from Sonoma County.