The Monarch butterfly (Danaus plexippus) is a milkweed butterfly (subfamily Danainae), in the family Nymphalidae. It is perhaps the best known of all North American butterflies. Since the 19th century, it has been found in New Zealand, and in Australia since 1871 where it is called the Wanderer. In Europe it is resident in the Canary Islands, the Azores, and Madeira, and is found as an occasional migrant in Western Europe. Its wings feature an easily recognizable orange and black pattern, with a wingspan of 8.9–10.2 centimetres (3½–4 in). (The Viceroy butterfly has a similar size, color, and pattern, but can be distinguished by an extra black stripe across the hind wing.)
The Monarch is famous for its southward migration and northward return in summer from Canada to Mexico which spans the life of three to four generations of the butterfly.