Below (ventral surface of wings): two large eyespots, considerably larger than those of Painted Lady. Compare, on the left, American Lady, Vanessa virginensis, and on the right, Painted Lady (Cosmopolitan), Vanessa cardui:
Dorsal wing surfaces: If present (it isn't always--see below), a white dot in the orange of the forewing distinguishes American Lady from the Painted Lady. Another easy-to-see character is the falcate (notched) wing-tip of the American Lady. In the Painted Lady the wing-tip is rounded. See these photos below for a detailed comparison:
The white spot is very small or absent in some specimens, including ones that appear to be fresh--examples:
Larvae are variable: greenish yellow with black bands to black with cream bands, numerous red-based branched spines; two prominent white spots on each segment. (1)
Much of North America south to Columbia and Venzuela. Also found, mostly at high elevations, on several islands in the Greater Antilles. Overwintering in the south and moving northward (usually well into Canada) varying distances during the spring and summer where it breeds and produces summer generations. Also sometimes encountered in western Europe, where it is likely a stray, and apparently established in the Canaries and Hawaii.
Larvae feed on Cudweeds and Everlastings.
Often found with Vanessa cardui and not obviously different unless one looks closely.
One of the few "numbered" butterflies, Hodges #4434
Replaced in South America by extremely similar V. braziliensis and V. altissima, which are both perhaps subspecies of V. virginiensis; and which if so, would make this a very wide-ranging species occurring pretty much through the entirety of the Americas. South American V. myrinna is also very similar and sometimes confused with the others, even though distinctly different.
The Vanessa Migration Project
--help contribute to scientific knowledge about these butterflies.