Northern Prairie Wildlife Research Center
Wingspan 3.2 cm. Forewing is a dull gray-brown with a central median band of pale gray. This geometrid is common and widely distributed in western North America. Moths fly in spring. Caterpillars feed on the foliage of species of Pinaceae such as spruce (Picea), Douglas-fir (Pseudotsuga menziesii), and western hemlock (Tsuga heterophylla).
Similar species: at least 40 species of similar appearing Hydriomena occur in western North America. The most common include Hydriomena renunciata with a pale green forewing and caterpillars that feed on the foliage of alder (Alnus); Hydriomena perfracta forewing is pink-gray, caterpillars feed on the foliage of blueberry (Vaccinium); Hydriomena irata is smaller, forewing with a white median band, caterpillars feed on foliage of oak (Quercus); Hydriomena edenata forewing with a large black dash along the inner margin.