Adults on wing in July and August depositing green eggs in clusters on host foliage. Douglas-fir is a major host in the lower mainland. They overwinter in these webs and move out from the web each day to feed when it is warm enough.
Mature larva has tufts of yellow and brown hair, sometimes with dorsal tufts of black hair.
Caterpillars pupate on tree or forest floor in June. The young dark caterpillars are one of the first insects to start feeding on Douglas-fir in the spring. We get many calls from the public in March after people have seen early season activity. Damage is usually spotty, this insect is generally controlled by its natural enemies. See HForest .