Northern Prairie Wildlife Research Center
Wingspan 4.8 cm. The wings are variable in color from pale gray to a dark black brown with wavy black lines and heavily speckled with dark gray spots. This species is the salt and pepper moth that has been cited as an example of industrial melanism in England. This geometrid is common and widely distributed in forests and woodlands of western North America. Moths fly in early to mid summer. Caterpillars are generalist feeders on the foliage of flowering trees and shrubs, particularly alder (Alnus), willow (Salix), and chinquapin (Chrysolepis chrysophylla).
Similar species: species of Cochisea lack the heavy speckling on the wings and fly in fall; species of Lycia (Geometridae) also lack the heavy speckling and fly in late winter or early spring.