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Pest Information

Plaster Bagworm

Plaster Bagworm

  • Latin Name: Phereoeca praecox
  • Common Name: Plaster Bagworm
  • Other Names: Wall bagworm

Pest Details

Plaster Bagworm
Plaster Bagworm
Plaster Bagworm
Plaster Bagworm


This moth may be native to Latin America and is more common in southern California than anywhere else in the U.S.


This moth is closely related to the Household Casebearer, which is discussed separately and which is a distinct species. It is often confused with the Casemaking Clothes moth because the larvae of both moths as well as the Household casebearer will create a small silk “case” for itself, camouflaged with debris from its local environment, and drag this case about as it wanders. Females deposit up to 200 eggs, cementing them to surfaces and on debris where larvae may find food. The larva immediately creates its silk case and it is a very active stage, wandering in search of food. While they are not well known it is likely they feed on detritus and bits of organic debris found within structures, but they also will feed on wool materials when they find them. Large numbers also have been found feeding on the growth of mycelia of decay fungi on structural wood. A complete life cycle from egg to adult moth requires about 2.5 months.


The silk case of the larva normally will be the only evidence that this moth is present, although a living larva will be inside. The case is usually dark and covered with bits of sand, soil, insect droppings, and fibers and other debris in the environment. The shape of the case is distinctive, being narrowed to extensions at each end. The larva is a nondescript white larva with a brown head. The adult moth is a dark gray or brown with 3 or 4 dark patches on the forewings and a tuft or light colored hairs on top of the head.

Characteristicts Important to Control:

It is necessary to find the infested materials in order to eliminate this pest. The larvae will be feeding in a protected place where insecticides will not be likely to contact them, so discovery of the source and disposal or treatment of it are needed. The larvae may also be vacuumed when found wandering in the general environment.

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