Northern Prairie Wildlife Research Center
Wingspan 2.9 cm. The male (photo) forewing and hindwing is variably dark red-brown to yellow with two narrow lines and hindwing is dark red-brown; female forewing and hindwing is more yellow with red-brown shading. This lasiocampid is very common and widely distributed in western North America. Moths fly in midsummer. Caterpillars are generalist feeders on the foliage of flowering trees and shrubs, particularly bitterbrush (Purshia tridentata), snowbrush (Ceanothus velutinus), maple (Acer), alder (Alnus), and oak (Quercus).
Similar species: Malacosoma disstria wings are typically yellow or pale brown, common and widely distributed, caterpillars are generalist feeders on foliage of flowering trees and shrubs.