Monarch Butterfly, the most common species of the milkweed butterflies. The monarch occurs throughout the world, mainly in North America. The adult has wings of a striking reddish-brown, with black veins and black borders with two rows of white dots. The wingspread is 10 cm (4 in). Each fall the monarch butterfly migrates south to California, Florida, and Mexico. The longest flight known for a tagged adult is some 2900 km (some 1800 mi) from Ontario to Mexico. Migratory groups congregate at the same places each winter, such as Pacific Grove, California, or the mountains
in central Mexico, where the trees may be completely covered with monarchs. In the two-year lifetime of most of the butterflies, the individual makes the trip twice. The females lay their eggs on the underside of milkweed leaves. The larvae feed on the milkweed plants and accumulate a poisonous substance that makes them distasteful to birds and other predators. The birds learn to recognize the butterflies' bright pattern and avoid them. The viceroy butterfly and the monarch are Mullerian mimics.
Scientific classification: The monarch butterfly belongs to the family Danaidae, order Lepidoptera. It is classified as Danaus plexippus.