- Eggs: Females lay eggs in summer. The eggs overwinter in felt-like cases and hatch in early spring.
- Larvae: Upon hatching, larvae travel to the tree’s leaves or needles to feed. Young larvae will eat all except for the main skeletal veins; mature larvae will eat the entire leaf. Larvae are brightly coloured with spots of bright red and yellow. They have 4 grey, bristly spots of long hair on their backs. The also have horn-like tufts of black hair at both ends. When fully grown, larvae may be 13 to 22 mm in length.
- Pupae: Tussock larvae are a nuisance as they travel along twigs, branches, and tree trunks to find a place to pupate. Their cocoon is dark grey.
- Adults: Adults emerge in late summer and are usually dull coloured and medium-sized. Males have smaller bodies with broad wings. Females have a heavier body and may or may not have wings. Those that have wings are poor fliers.
- Defoliation: Tussock larvae can defoliate plants and trees in areas of large infestations. The larvae will eat both hardwood and many species of conifers.
- Preventive tools: Not applicable
- Physical tools:
- Remove larvae by hand. NOTE: Wear gloves as hair on larvae may irritate your skin.
- Biological tools:
- Parasitic wasps can control tussock moth populations.
- Least toxic chemical tools: Not applicable