Pest profile

Household Casebearer

Phereoeca uterella · Lepidoptera: Tineidae[2]

Those small, flat gray cases on walls and ceilings are made by household casebearer larvae, often called plaster bagworms.[1]

Household casebearer case, a flat gray seed-shaped case, on a red wall
Household casebearer case, a flat gray seed-shaped case, on a red wall. (c) Helio Lourencini, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • The larval case is slender, flat and spindle-shaped, like a cantaloupe or pumpkin seed, silk-lined and open at both ends.[1]
  • Cases turn up under spider webs, in bathrooms, bedrooms, garages, on curtains, wool rugs and shaded exterior walls.[1]
  • Adults are small moths that hold their wings tented over the body.[1]

Look-alikes

Look-alikeHow to tell them apart
BagwormsIt's often called plaster bagworm, but true bagworms are a different moth family.[1]

Where it lives

It needs high humidity and is known from Florida and Louisiana, with records from Mississippi and North Carolina.[1]

US map: public records from 9 states since 1990 (GBIF).

Biology and life cycle

A female lays about 200 eggs in cracks and floor edges over a week; larval life lasts about 50 days in warm conditions.[1]

Damage and signs

  • Larvae can feed on woolens, silks, felt and spider web debris, making it a potential household pest.[1]

Health risk

UF/IFAS describes it as a potential household pest of fabrics, with no risk to people.[1]

Control

Prevention

Regular cleaning and air conditioning have reduced problems with this species.[1]

Traps and physical control

Pick off or vacuum cases and remove spider webs.[1]

Common questions

What are the little flat cases on my walls?
Household casebearer larval cases, sometimes called plaster bagworms.[1]
How do I get rid of them?
Vacuum or pick off the cases and clear spider webs.[1]

Sources

  1. University of Florida IFAS Extension (Featured Creatures), “Household Casebearer, Phereoeca uterella (EENY-003).” edis.ifas.ufl.edu/publication/IN129 (accessed 2026-10-06)
  2. iNaturalist, “Phereoeca uterella taxon page (order and family).” www.inaturalist.org/taxa/363376 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.