Household Casebearer or Plaster Bagworm
Scientific Name: Phereoeca uterella
Order & Family: Lepidoptera (Moths and Butterflies), Tineidae (Fungus Moths/Clothes Moths)
Size: Larvae (in their case) are usually about 10-15 mm (0.4-0.6 inches) long. Adults are small moths, about 6-10 mm (0.24-0.4 inches) in wingspan.
Natural Habitat
Typically found indoors, especially in damp, undisturbed areas like bathrooms, attics, closets, and garages. They feed on natural fibers and detritus.
Diet & Feeding
The larvae feed on a variety of materials including spiderwebs, dead insects, animal hairs, woolen products, silks, and occasionally synthetic fibers. They are also known to eat fungi and detritus.
Behavior Patterns
The most distinctive behavior is the larva's construction of a flattened, silken case that is covered with debris such as sand, lint, and insect droppings. The larva lives and moves within this case, carrying it everywhere. When it pupates, it seals itself inside the case. The adult moths are small, dark, and rarely seen, flying mainly at night.
Risks & Benefits
Potential risks include damage to natural fiber textiles, carpets, and stored goods, though they are generally considered a minor pest unless infestations are severe. They do not bite or sting and are not known to transmit diseases. They can be beneficial by consuming discarded lint, cobwebs, and dead insect matter in neglected areas.
Identified on: 9/28/2025