The painted lady butterfly lives mainly in open or disturbed habitats, where their larval foodplants (various thistles) can be found in abundance.
Eggs are laid singly on the uppersides of hostplant leaves in the spring. Larvae hatch in a few weeks and feed on the hostplant while living in silk nests on the uppersides of the leaves. Larvae pupate in early summer on the undersides of vegetation, suspended by short stalks. Adults emerge from the pupae either in late summer of that year or in early spring of the following year, depending on temperature. Generally, in the north, pupae are the overwintering stage, while in the south adults are the overwintering stage. In either case, the adults (newly emerged from the pupae or having overwintered) mate and produce new eggs in the spring, dying shortly thereafter.
Painted lady butterflies are well known for their long migrations (several thousand kilometers!) north in the spring and early summer and south in the late summer and fall. Often, in Vancouver, hundreds of them will show up overnight where none had been before … quite an amazing sight to see! And for you trivia buffs, the painted lady is the most widely distributed butterfly in the world, occuring on six of the seven continents.