7/8-1 1/8" (22-28 mm). Wings angular. Above, uniform deep mahogany with fine, blacker scalloping; lacks wide, central darkened bands; silver-green metallic markings form continuous band. Below, yellow to orange-brown with black to lead-gray flecks.
Northern Metalmark similar but darker and duller above, more rounded; occurs in drier habitats. Little Metalmark smaller, with more rounded wings and more red.
Sculptured egg tucked under leaves of young swamp thistle (Cirsium muticum), upon which caterpillar feeds. Caterpillar pale green with plumelike hair, few or no black spots
along back; overwinters partially grown. Chrysalis has silken girdle, surrounds itself with fuzzy hair of caterpillar woven into loose mat.
1 brood; July-August.
Wet meadows, swamps, and bogs.
W. Pennsylvania across N. central Great Lakes States to SE. Minnesota; recorded once in New England.
Swamp and Northern metalmarks are best distinguished by habitat and geography. The Swamp Metalmark is found in more northern and wetter areas. Although basically they do not overlap, together the ranges of the Swamp, Northern, and Little metalmarks cover most of the United States east of the Mississippi. This pattern suggests that these 3 metalmarks may have developed relatively recently from a common ancestor.