In the world of insect migration, monarch butterflies rule the sky. Every fall, hundreds of millions of these black, orange and white insects migrate thousands of miles from the eastern United States and Canada to the mountains of central Mexico, where they spend the winter. By late February, they begin their return journey north.
“We’re estimating that many of these butterflies fly more than 5,000 miles in their lifetime,” said Chip Taylor, who runs the Monarch Watch Program at the University of Kansas. He and his team place small tags on monarchs’ wings to monitor where they fly.
“Monarchs have a biological clock in their brain, but also one in their antennae that tells them when the sun rises and sets,” Taylor said. By keeping track of the sun’s location in the sky, these two body parts act like a calendar and compass for the butterflies.
Monarchs that spend the winter in Mexico live eight or nine months, longer than any other monarchs. They begin their migration in late summer or early fall and reach Mexico in late fall and early winter, covering an average of 25 to 30 miles a day (about the distance from Washington, D.C., to Annapolis, Maryland).
They begin their flight back to the southern United States in late February and March. Along the way, each female lays a few hundred eggs. As the migrating generation dies off a month or two later, the new generation continues the springtime migration north and reaches the eastern United States and Canada in late spring and early summer. They have children and grandchildren of their own, and the cycle continues.
Migrating monarchs face many dangers, including storms and predators. But according to Taylor, their biggest threat is habitat loss.
Like all living things, monarchs need food, water and shelter to live. Adult monarchs eat nectar from flowers, and their larvae (the caterpillar stage) eat milkweed plants. In the United States, about 6,000 acres of land are paved over each day for roads and buildings, leaving less space for for butterfly habitats.
But kids can help. You can raise the caterpillars to butterflies, then release the adults. “Monarch Watch provides monarch caterpillars to hundreds of schools,” Taylor said.
Kids also can plant milkweed and other butterfly-friendly plants in their gardens, or catch and tag adult monarchs before migration begins.
“Catching butterflies isn’t as easy as it may sound,” Taylor said. “There are some skills involved.” But every tag helps researchers learn more. And when it comes to these tiny traveling butterflies, there is much to discover.