Cathy observed these caterpillars feeding on her Red Osier Dogwood (Cornus sericea), an attractive shrub with ruby-colored twigs. Western Red-humped Caterpillars are generalist hardwood feeders and choose from a wide range of trees and shrubs in the beech, birch, rose, maple, buckthorn, and heath families… and more. The larvae are sometimes pests in fruit orchards. The nocturnal moths on the other hand, do not feed, and are commonly found in mid- to late summer. Reportedly, they are not as strongly attracted to lights as most other night-flying moths. This species ranges from southern BC, Washington, and Idaho south to southeastern California. We’ll add western Montana to that list!
Size: Forewing length 14 – 16 mm (adult)
Photos by: Cathy Casali Kowalski on 8/25/22 in Potomac, MT