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Monarch butterflies undergo one of the most impressive mass migrations in the insect world. Each fall, these butterflies head south to avoid freezing temperatures and frost that would otherwise kill them. Populations west of the Rockies overwinter on the Central Coast of California and can be seen in huge assemblages at certain areas along the coast. They seem particularly fond of eucalyptus groves. Monarch populations east of the Rockies migrate all the way south to Mexico. This great migration takes longer than the 2 month life expectancy of an adult monarch, so remarkably, a single north/south migration spans multiple generations.
Santa Cruz, California