Tussock moths are generally white (like the gypsy moth) or gray, and the adult does not feed and only lives for a short time. The white-marked tussock moth is found to the east of the Rockies and, although the adult is a rather inconspicuous dark gray with brown and black markings, the caterpillar is very distinctive with its red head and three tufts of long hair. It has white or yellow mid-dorsal tufts. The bright red spots are glands. The caterpillar feeds on woody plants including willow, oak, elm and hackberry.

The adult female cannot fly and lays several hundred eggs on the cocoon from which she emerges. The eggs are covered by froth and over-winter in this stage.

The hairs can cause an allergic reaction on skin in sensitive areas.