Which butterfly is famous for the longest annual insect migration?

The monarch butterfly is famous for the longest annual insect migration.

Each year, monarchs in North America travel south to overwintering sites in central Mexico or coastal California. In spring, they begin moving north again, breeding along the route and producing several generations before reaching the northern parts of their range.

The complete round trip cannot be made by one individual. Monarchs born late in summer enter a non-reproductive state and may live for months, allowing them to make the southward journey and much of the return trip. Earlier generations usually live only a few weeks.

This migration is unusual because the butterflies navigate to seasonal sites they have never personally visited. Researchers link their orientation to the Sun, an internal biological clock, and inherited directional behavior. Monarchs elsewhere in the world may migrate too, but the best-known and most extensively studied migration is the North American one. The species is often confused with the viceroy butterfly, which resembles it in color but is a separate species.