Identification
Below: 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:
Above: If present (it isn't always), a white dot in the orange of the forewing distinguishes this from Painted Lady. See this photo for a detailed comparison of the upperwing surfaces:
Larvae are variable: greenish yellow with black bands to black with cream bands, numerous red-based branches spines; two prominient white spots on each segment.
(1)Range
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.
Food
Larvae feed on Cudweeds and Everlastings.
Remarks
Often found with Vanessa cardui and not obviously different unless one looks closely.
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 occuring 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.
Internet References
The Vanessa Migration Project. Help contribute to scientific knowledge about these butterflies.