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A very large (8.5-11.5 cm wingspan) long-winged moth. The body is brown edged with longitudinal black stripes. The doubled postmedian line on both wings is the only well developed cross line. There are also a number of black longitudinal streaks on the outer half of the forewing and small, light discal spots. Our other large dark sphinx moths from south of the boreal forest are grey, not brown. The adults are similar, but females are larger than males. The larvae are large, pale green with granular skin and pale diagonal lateral streaks. They are easily identified by the four prominent horns on the front end, hence the other common name, the Four-horned sphinx.

The adults are nocturnal and come to light. There is a single annual brood, which overwinter as pupae. Mature larvae are most often encountered after they wander from the host tree and seek a place with loose soil in which to pupate. The only Alberta record is for June 3, 2004.

This eastern species reaches the western limit of its range in southeastern Alberta. The presence of the very fresh female collected near Jenner (illustrated above) suggests that this was not a long-distance immigrant but part of a resident Alberta population. The larvae was photographed in central SK.