Minnesota Now with Nina Moini

From Minnesota to Mexico: How do monarchs know where and when to go?

In the Oyamel forest
In this 2008 file photo, monarch butterflies gather in the Oyamel forest of El Rosario sanctuary in Angangueo, Michoacan, Mexico. Millions of monarch butterflies establish themselves every year in this part of Mexico after crossing through the U.S. from Canada.
Luis Acosta/AFP/Getty Images 2008