Monarch butterflies complete two migrations every year. The first occurs when early generations of monarchs begin migrating from Mexico northward through the United States in early spring. The monarch butterfly instinctually completes this first migration to escape high temperatures and to begin their breeding season. Then, in late summer, the last generations of monarchs begin the journey back to Mexico, traveling southward through the United States to overwinter before temperatures become too cool and to seek more abundant food resources.

The last generation of monarch butterflies to migrate south is called the super generation, living up to 8 months in a semi-dormant state, kicking off the next cycle the following spring. Seasonal changes drive monarch butterfly migration, with rising and falling temperatures and day length serving as key indicators of when to begin migrating.