Monarch butterflies

Monarch butterflies are especially noted for their massive southward migrations from August through October. Female Monarch butterflies deposit eggs for the next generation during these migrations. The population east of the Rocky Mountains overwinters in Michoacán, Mexico, and the western population overwinters in various sites in central coastal California. The length of these journeys far exceeds the lifetime of any given butterfly. How the species manages to return to the same overwintering spots over a gap of several generations is still subject of research.