Household Casebearer (or Plaster Bagworm)
Scientific Name: Phereoeca uterella (sometimes referred to as Phereoeca allutella in older texts)
Order & Family: Order: Lepidoptera, Family: Tineidae
Size: Larval case is typically 8-13 mm (0.3-0.5 inches) long.
Natural Habitat
Typically found indoors in dry, dusty areas of homes, particularly on walls, floor molding (baseboards), carpets, and underneath furniture. They prefer humid climates.
Diet & Feeding
The larvae feed on keratin-rich debris including spider webs, old insect skins, wool fibers, hair, and sometimes dried plant material.
Behavior Patterns
The larva constructs a distinctive flat, pumpkin-seed-shaped protective case out of silk and debris (sand, dust, fibers) which it carries around. It can retract fully inside when threatened. They eventually pupate inside this case.
Risks & Benefits
Risks: Generally harmless to humans and pets (they don't bite or sting). However, in large numbers, they can be minor pests that damage wool clothing, rugs, or fabrics. Benefits: They act as cleaners by eating spider webs and dead insects.
Identified on: 2/7/2026