Lepidoptera species migrate on all continents except Antarctica; they migrate from or within subtropical and tropical areas. The terms migratory butterfly and migratory moth are location-bound: they are only known as such in the areas where the species cannot establish themselves permanently.
By migrating, Lepidoptera species can avoid unfavorable circumstances, including weather, food shortage, or over-population. Like birds, there are Lepidoptera species of which all individuals migrate, but there are also species of which only a subgroup of the individuals migrate.