Banded Woolly Bear Moth

The banded woolly bear is the larval stage of the Isabella tiger moth, a common North American species in the tiger moth subfamily (Arctiinae) of family Erebidae. While the caterpillar is instantly recognizable and culturally famous, the adult moth is a modest, sparsely marked insect in shades of yellow-orange to tan that draws far less attention.

The caterpillar's distinctive banding, a black segment at each end with a reddish-brown band in the middle, has made it the subject of long-standing folk beliefs about predicting winter severity based on the relative width of the bands, although the pattern actually reflects the caterpillar's age and molt stage rather than seasonal forecasting. It is one of the most frequently photographed and discussed caterpillars in North America each autumn.

Ecologically, this species is a hardy generalist herbivore capable of surviving freezing winter temperatures as a partially grown larva, an unusual adaptation among moths that allows it to overwinter in exposed leaf litter rather than underground or in a protected cocoon.

• Caterpillar: densely bristled with short, stiff hairs; black at both the head and tail ends with a broad rust-brown or reddish band across the middle segments.
• Curls tightly into a ball when handled or disturbed, a common defensive posture for this and related woolly bear caterpillars.
• Adult moth has yellowish-orange to tan forewings, sometimes with a few small dark spots, and a stout, hairy body with an orange abdomen marked by black dots.
• Adult wingspan is moderate for a tiger moth, with relatively plain, unpatterned wings compared to more boldly marked relatives.
• Lookalikes include other banded arctiine caterpillars, but the specific black-rust-black banding is the most recognized pattern of this species.

Widespread across the United States and southern Canada in open habitats such as fields, meadows, gardens, and woodland edges. Caterpillars are most visible in autumn as they travel over open ground searching for sheltered overwintering sites such as leaf litter, bark crevices, or under logs. Adults fly at night in late spring through summer.

The caterpillar is a generalist feeder on a wide range of low plants, grasses, and weeds, and is famous for actively wandering across roads, sidewalks, and lawns in fall. It has a natural freeze tolerance that allows it to survive winter in a dormant state as a partly grown larva, resuming feeding briefly the following spring before pupating. Adults are nocturnal fliers with unremarkable, subdued coloring that serves as camouflage against tree bark and dry vegetation, and both stages are preyed upon by birds and other insectivores.

Eggs are laid in summer and hatch into small caterpillars that feed and grow through several molts before winter. Unlike most moths, the partially grown caterpillar overwinters in a dormant, freeze-tolerant state rather than as an egg or pupa. In spring it resumes feeding briefly, then spins a cocoon incorporating its own bristly hairs and pupates, emerging as an adult moth in late spring to summer; typically one generation occurs per year in northern regions, with two possible farther south.