Other Common Names
Cosmopolitan, Thistle Butterfly
Explanation of Names
cardui = latin for "of thistle" referring to the caterpillar's food plant.
Similar to the also common American Lady. Wings look more "rounded" in overall shape in American Lady, and outer margin of front wing is more excavated/concave in American Lady. Upper front wing with large subapical oblong spot near front margin always white in Painted Lady; can be white or orange in American Lady. Five small, instead of two large eye spots on the under hind wing. Compare, on the left, American Painted Lady, Vanessa virginensis, and on the right, Painted Lady (Cosmopolitan), Vanessa cardui:
See this photo for a detailed comparison of the upperwing surfaces:
Also similar is West Coast Lady, Vanessa annabella, but Painted Lady has the large subapical spot near front edge of front wing white; the discal cell of front wing has two (roughly) triangular dark spots; and dark spots on the upper hind wing are most often not or only faintly centered with blue (blue centers more common in the Southwest than elsewhere). In West Coast Lady the oblong spot is a bit larger and orange; there is a dark bar crossing discal cell; and dark spots on the hind wing above are usually prominently centered with blue. Undersides are very similar, but the same pattern differences show on under front wing as on upper side, and eye spots on the hind wing are usually round or oval in the Painted Lady, while at least some are usually heart or kidney-shaped in West Coast Lady. Orange coloring of West Coast Lady less likely to look pinkish than in other two Lady species (where the hue is more varied).
Painted Lady (left); West Coast Lady (right)
Caterpillars have branching spines and pale narrow yellow/cream striping on generally dark bodies. Young larvae often exhibit alternating light and dark spines (see below) although this characteristic is not restricted to this species.
Worldwide, except South America and Antarctica, irruptive--sometimes not present in a given locality for several years then abundant for one year. A rare stray in Australia, except represented there by very similar and closely related Vanessa kershawi, which is often considered to be just a subspecies of V. cardui.
Spring to Freezing in Autumn in most regions; year-round in mild winter climates in South and particularly in the Southwest. Migrates north in Spring and recolonizes areas where winters are too cold for it to survive year-round. Sometimes spring migrations are made up of spectacular numbers of individuals. Autumn movement back southward is more sporadic and not as obvious. Seems to overwinter mostly as pupae in areas where winters are too cold for adults to fly, but mild enough for survival.
Adults take nectar from a variety of flowers, especially Asteraceae. Caterpillars feed primarily on Asteraceae and Malvaceae, especially Thistles, Burdock, and Hollyhocks. Many other plants are used occasionally, including Nettle, Alfalfa, Soy Bean, Beet, Borage, Plantain, etc.
See notes under "Season" above. Generally there are multiple generations per year, with fewer in the north than in the south (depending on lenght of warm season, and on when adults first arrive in an area each year). Does not overwinter in areas with severe freezing winters, may overwinter as pupae and perhaps larvae in mild winter regions, and flies year-round where freezing is rare and winters are sunny.
Eggs are usually laid singly on leaves of host plants, and larvae produce nests by weaving leaves together or attaching edges of a rolled leaf. There may be several nests on a plant, but usually only one larva per nest. Development time varies, but can be as little as three weeks from egg to adult in favorable conditions.
Occurence is irregular in many regions, especially northward in parts of Eurasia and North America, and near North American Atlantic Coast. "Invasions" seem to usually be spaced at long intervals of several years in such places.
Migration best studied in Europe, in the fall it migrates from England to North Africa.
This species is unusual in that an artificial food has been developed for the larvae. Painted Lady butterflies are often available mail-order or at bug fairs and other natural history venues, generally in the form of immature larvae in a small cup of glue-like artificial food. They are thus commonly and easily raised especially in elementary school classrooms. See here
for one source.