Painted Lady butterflies inhabit every continent except Australia and Antarctica You can find painted ladies everywhere from meadows to vacant lots. Although they live only in warmer climates, painted ladies often migrate to colder regions in spring and fall, making them the butterflies with the widest distribution of any species. 

The painted lady is an irruptive migrant, meaning that it migrates independently of any seasonal or geographic patterns. Some evidence suggests that painted lady migrations may be linked to the El Niño climate pattern. In Mexico and some other regions, it appears that migration is sometimes related to overpopulation. The migrating populations that move from North Africa to Europe may include millions of butterflies. In spring, painted ladies fly low when migrating, usually only 6 to 12 feet above the ground. This makes them highly visible to butterfly watchers but also makes them susceptible to colliding with cars. At other times, painted ladies migrate at such high altitudes that they are not observed at all, appearing unexpectedly in a new region. 

Thistle, which can be an invasive weed, is one of the painted lady caterpillar’s favorite food plants. The painted lady probably owes its global abundance to the fact that its larvae feed on such common plants. The painted lady also goes by the name thistle butterfly, and its scientific name— Vanessa cardui —means “butterfly of thistle.”

 https://www.thoughtco.com/facts-about-painted-lady-butterflies