Tussock Moth Caterpillar

Tussock moth caterpillars belong to the genus Orgyia, part of the tiger and tussock moth subfamily, and are best known for their striking hair tufts arranged in tight brush-like clusters along the back. These larvae feed on a wide range of deciduous trees and shrubs and are commonly noticed clinging to bark, fences, or window screens as they wander in search of a pupation site.

The adults of this genus show extreme sexual dimorphism: males are winged and fly to find mates, while females of many species are flightless with vestigial wings and never leave the cocoon area. The caterpillars themselves are one of the more visually distinctive larvae found in North American gardens and woodlands.

• Four dense, brush-like tufts of pale yellow to white hair set upright along the back (the "tussocks")
• A pair of long, dark pencil-like hair plumes projecting forward from behind the head
• One or two similar long hair plumes projecting backward from the rear
• Body color varies by species but often shows a black or gray background with red or orange spots along the sides
• Head capsule is typically bright red or orange
• Lookalikes include other hairy caterpillars such as woollybears, but the upright brush tufts are distinctive to tussock moths

These caterpillars are widespread across North America in deciduous forests, orchards, hedgerows, and urban landscaping wherever their host trees grow. They are especially noticeable in mid to late summer when mature larvae wander from feeding trees to find sheltered spots to spin cocoons.

Tussock moth larvae are foliage feeders on a broad range of trees and shrubs, sometimes causing noticeable defoliation in outbreak years, which is why the species is regarded as a garden and orchard pest by growers. The hair tufts serve as a defense against predators, and the caterpillar is otherwise a slow, deliberate crawler. It plays a role in forest food webs as prey for birds and parasitic insects that specialize on tussock moth larvae.

Females lay eggs in a frothy mass on or near the cocoon from which they emerged, since flightless females cannot disperse far. Larvae hatch and pass through several instars while feeding on leaves, developing their characteristic tufts as they mature. Mature caterpillars spin cocoons incorporating their own body hairs, often on tree bark or nearby structures, and pupate there. Depending on species and region, tussock moths may produce one or more generations per year, typically overwintering as eggs.