Pycnopsyche scabripennis

Larvae of the giant red sedge inhabit swift, cool forested streams across eastern North America, where they construct heavy architectural protective cases from fallen leaves, bark fragments, and mineral grains. Late in the season, mature larvae transition their cases almost exclusively to stone ballast to withstand autumn currents before pupating underwater. Adults emerge in great numbers from late August into October, fluttering through the riparian canopy at dusk and mating before females deposit gelatinous egg masses along damp riverbanks.