Thousands of beautiful orange-black and white monarch butterflies fly a huge distance every year to get from their breeding sites in the northern U.S. and Canada to their wintering locations in Mexico and California. Colorado, especially its eastern side, lies on monarch migration routes. Butterflies usually fly along the eastern side of the Rockies. Every fall, starting from September and ending in mid-October, it's possible to witness swarms of monarchs in the gardens, parks, and open fields. After cold weather ends, monarch butterflies fly back north to lay eggs. They can only do it on the leaves of milkweed. Their spring migration takes place between March and June. However, it's usually not as massive as autumn migration.
Butterflies are looking for a place to snack on nectar so wildflower fields and gardens are their primary targets. Large numbers of monarch butterflies are reported in John Martin Reservoir State Park in the southeastern part of the state. In the north, they are often spotted in the Gardens on Spring Creek in Fort Collins. as well as in parks around Denver and especially in the Denver Botanic Gardens. It's also a great idea to stop by the Butterfly Pavilion in Denver. Not only have they a vast pollinator garden designed to attract butterflies, but the Pavilion also runs Monarch Magic days from mid to late September. During these days you can learn a lot about monarchs and see more than 200 non-migrating butterflies in their tropical conservatory.