Larvae spin webs enclosing leader and branch tips. When the population density is normal, grey cocoons may be found on the underside of old foliage. When the population density is high, additional cocoons may be found on branches, on the trunk, or on understory vegetation. Adult insects are charcoal-brown moths. Larvae go through several stages of development.
All stages of development are hairy.
If you have a defoliator which has no hair, it's not tussock moth. The female, who does not fly, lays eggs on her cocoon anywhere from August through October. These eggs are mixed with hairs from her abdomen, held together with a gelatinous substance. Eggs overwinter in a mass and hatch from late May to late June. Larvae initially feed on the underside of new needles, then switch to older needles and next year's buds.