Household Casebearer (often referred to as Plaster Bagworm)
Scientific Name: Phereoeca uterella / Phereoeca alluvial
Order & Family: Lepidoptera (Order), Tineidae (Family)
Size: Larval case is typically 8 mm to 13 mm (0.3 to 0.5 inches) in length.
Natural Habitat
Typically found indoors in humid climates, often on walls, baseboards, underneath furniture, and inside closets. They are common in tropical and subtropical regions like Florida (USA) and Southeast Asia.
Diet & Feeding
The larvae feed on old spider webs, wool, human hair, pet fur, and dead insect parts. They are detritivores.
Behavior Patterns
The larva constructs a protective case (often shaped like a flat pumpkin seed or watermelon seed) out of silk and debris (dust, sand, hair) which it carries around. It has openings at both ends of this case, allowing it to turn around inside and feed from either end. The adult stage is a small moth.
Risks & Benefits
While not harmful to humans (they do not bite or sting), they are considered household pests because they can damage woolen fabrics, carpets, or furs. However, they generally prefer feeding on cobwebs and dust bunnies.
Identified on: 2/21/2026