Household Casebearer (also known as the Plaster Bagworm)
Scientific Name: Phereoeca uterella (formerly Phereoeca walsinghami)
Order & Family: Order: Lepidoptera, Family: Tineidae
Size: Larval case is typically about 8-13 mm (0.3-0.5 inches) long.
Natural Habitat
Typically found indoors in warm, humid climates; they thrive in closets, garages, under spiders' webs, and on stucco or plaster walls.
Diet & Feeding
Detritivores; they feed on old spider webs, wool, hair, lint, dead insects, and textile fibers.
Behavior Patterns
The larva builds a flattened, pumpkin-seed-shaped or spindle-shaped case out of silk and debris (sand, soil, frass) which it drags around while feeding. The case has openings at both ends so the larva can turn around inside without leaving the shell.
Risks & Benefits
Risks: Generally harmless to humans and pets (they don't bite or sting) but can be a nuisance pest in homes; may damage woolen fabrics or rugs in large numbers. Benefits: They clean up spider webs and dead insects, though this benefit is usually outweighed by their nuisance status.
Identified on: 2/13/2026