Today’s Factismal: Every year, Monarch butterflies migrate from Mexico to the Great Lakes and back again; the journey takes four generations to complete!
Perhaps the best known of the 24,000 species of butterflies is the Monarch. This lovely insect is found in gardens and parks all across North America, and is even an occasional visitor to places like the Bahamas, Australia, Europe, Thailand, and the Canary Islands. This is a butterfly that gets around!
And it is no wonder that the Monarch is found in so many different parts of the globe. Even when it stays in its own backyard, the Monarch migrates from its winter home in central Mexico up to its summer home in the Great Lakes region. That’s a journey of more than 2,000 miles. Because the Monarch can only fly about ten miles per hour, it takes the butterfly nearly two months to make the trip. But, because Monarchs only live for a month and a half on average, that means that no individual actually makes the complete migration.
Instead, what happens is that the females that start out in Mexico will lay eggs along the journey. Those eggs hatch into caterpillars that feast on milkweed and other noxious plants; the accumulated poisons in the caterpillar make it an unpalatable meal for birds, which makes the caterpillars safer. After the caterpillars change into butterflies, they continue the migration until the second generation arrives in the northern range. There they lay eggs for the third generation that will live in the area until it is time to head back south. The third generation lays eggs somewhere during the migration back to Mexico and it is that fourth generation that will complete the migration and spend the winter in a sort of suspended animation known as diapause; this lasts until the end of winter, when the migration cycle begins again.
There is still much to learn about the Monarch migrations. If you’d like to help by spotting the butterflies in your area, then why not take a look at the Journey North website?