The monarch butterfly (Danaus plexippus) is world-famous for its long-distance migration from Canada and the northern U.S. to California and Mexico, and is a familiar sight in Florida as well.

Monarch butterflies migrate to the central and southern California coasts, if they’re from west of the Rocky Mountains, and Mexico if they’re coming from the East Coast.

The arrival of monarchs in the forests of central Mexico happens around the time of the local celebration Día de los Muertos (Day of the Dead), November 1-2. Tradition holds that the butterflies play a part by guiding home the spirits of the departed. The celebration is intended to teach the importance of ancestors, and of death giving way to new life. During fall migration, monarch butterflies also embody the cycle of life and death, and their return north the following spring spans multiple generations and thousands of miles.

The USDA’s Natural Resources Conservation Service has reported that monarch populations have decreased significantly over the last 20 years, in part because of the decrease in native plants, including milkweed, which they feed on while they are caterpillars.