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Bagworm larva
(John Obermeyer, Purdue University)
Common Name: Bagworm - larva
See also: damage

Scientific Name: Psychidae: Thyridopteryx ephemeraeformis

Status: common pest of evergreens and shrubs

Damaging Stage: caterpillar

Biology: Adult male moths are black with clear wings but are very seldom seen or collected. The wingless adult female does not leave the bag after pupation, so it is also not commonly seen. The small football-shaped bags are the most noticeable form of the insect and are commonly found hanging from leaves and twigs.

Bagworm eggs hatch in midsummer and the larvae crawl out of the bottom of the bag. There may be as many as 300 eggs per bag. Larvae are light brown or tan, although some may have a mottled appearance. The small caterpillars spin silken strands that are either caught by the wind and dispersed or are wrapped around tree branches. From there they begin creating small silk shelters woven together with bits of foliage (bags) from their environment. Bagworms live within these bags for protection and enlarge them as they grow. They may grow to 2 inches or more in length.