Color and markings are highly variable. Fringes on forewing are mostly black with some white, those on the hindwing are mostly white with a few black patches. Forewing ranges from brown with black borders through brownish gray with paler borders to pale gray with no borders. Dashes, submarginal line, and cell spot are usually weak. Hindwing is gray to yellow-gray with a black border and a black median line which ranges from distinct to diffuse.
(From BMNA site)
According to The Hawk Moths of North America by James Tuttle, this species can be separated from the similar Northern Apple Sphinx (Sphinx poecila) by the dark shading in the submarginal area of the forewing. In S. poecila, the submarginal area is concolorous with the rest of the forewing.
Southeastern New York and New Jersey, south to central Florida; West through southern Illinois, Colorado, and Utah; North through the Rocky Mountains to Manitoba
Coastal barrens, bogs, and deciduous forests.
May-September in most of the range.
From February-April in Florida.
Larva feed on: Apple (Malus), sweetfern (Myrica), Carolina rose (Rosa carolina), blueberry and huckleberry (Vaccinium), white spruce (Picea glauca), American larch (Larix laricina), and alder (Alnus).
(From the BMNA site)
Larva pupate in soft soil.