Northern Prairie Wildlife Research Center
Wingspan 5.0. Forewing is gray with narrow black lines; hindwing is solid gray without markings; thorax is gray with two narrow black lines; abdomen with black and gray lateral spots. This sphingid is widely distributed in dry forests with cedars in the Pacific West and is particularly abundant in juniper woodlands east of the Cascade Mountains. Moths fly in midsummer. Caterpillars feed on the foliage of western red cedar (Thuja plicata) and juniper (Juniperus).
Similar species: Sphinx dollii occurs in the Southwest and southern Rocky Mountains, caterpillars feed on juniper; Sphinx vashti is larger, hindwing with a black band, caterpillars feed on the foliage of snowberry (Symphoricarpos albus).