Home / Erebidae Moths / Western Tussock Moth (Orgyia vetusta)

Western Tussock Moth (Orgyia vetusta)

The western tussock moth is a member of the family of Erebidae moths. French lepidopterist Jean Baptiste Alphonse Déchauffour de Boisduval first described this species in 1852.  Its species name was Hemerocampa vetusta, changed to Orgyia vetusta.

Western Tussock Moth


Scientific Classification

  • Family: Erebidae
  • Genus: Orgyia
  • Scientific Name: Orgyia vetusta

Description and Identification


Initially, after hatching, the larvae appear black with long bristles. However, once they mature, they develop red and yellow spots, and the hairs get reduced to four median gray-haired tufts. They are 25 – 50 mm long.

Western Tussock Moth Caterpillar



After maturing, the larvae begin to pupate in a cocoon made of discarded larval hairs.

Western Tussock Moth Cocoon


Adult Moth

Sexual Dimorphism: Present.

The females are completely flightless as their wings are too short to allow for flight.

Color and Appearance

Forewing: When opened, the wings are dark, outlined in gray, with two irregular dark markings intersecting at 1/3rd and 2/3rd of their length. When closed, they form a roughly triangular outline.

Hindwing: When opened, the wings are brown. When closed, they are barely seen.

Average wingspan: 25-38 mm

Flight pattern: Erratic, dependent on the location of females.

Season: April through July

Orgyia vetusta



Females lay 125-300 eggs in a single egg mass, usually on their old pupal cases.

Western Tussock Moth Eggs


Quick Facts

DistributionThe western part of North America, including the Pacific States and British Columbia; also, states like Louisiana and Idaho
HabitatParks and walking trails
Lifespan of AdultsAround 3 months
Host PlantsApple, apricot, ceanothus, cherry, citrus, oak, pistachio, plum, prune trees, and willow
Adult DietDoes not feed

Did You Know

  • The caterpillars sometimes balloon themselves with the help of a silk thread from one location to another.
Western Tussock Moth Image


Western Tussock Moth Picture


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