Each year, Vanessa cardui makes huge, multi-generational, mass migrations up to 15000 km long in the Palearctic. In the spring, these butterflies move northward from their overwintering places in Africa, through the Mediterranean, to much of the European continent, and they then migrate back in the fall. Vanessa cardui uses favorable high altitude winds to move rapidly across the continents. Millions of butterflies partake in these migrations, though the numbers fluctuate every year. The migration allows these butterfly populations to take advantage of the changes in resources as the seasons change, moving north in the summer to avoid the hot temperatures in Africa, and moving south again to avoid the cold winters of northern Europe. This pattern is similarly reflected in the United States, where V. cardui migrates from Mexico to the northern United States and Canada.
Vanessa cardui mates along the way, quickly producing more generations. Populations begin to migrate northwards in March and April, and produce local generations as soon as May and June along the way. The migrants do not make it to the northern parts of Europe til late May and June. The Painted Ladies continue to breed, and by late August they are heading south again. They also stop to breed along the return migration, producing more generations in September and October. Breeding is fairly low in the winter. (ADW)