Monarch Migration

Flower & Garden Magazine, August, 1999 by Jennifer Curry

Hard as it is to believe, the beautiful and delicate wings of the monarch carry this butterfly from as far north as Canada as it heads toward Mexico every fall, travelling thousands of miles. While the scientific community puzzles over how a creature that weighs only half a gram can make such a treacherous journey, the backyard conservationist can simply enjoy these colorful visitors every fall and spring.

Although you aren't likely to see a large cluster of butterflies migrating like a flock of birds, you will notice monarchs everywhere in the fall. In the North, gardeners will start to see butterflies migrating as early as the end of August. September and October are the main months to look for the migration in the rest of the country. In the spring, the monarchs retrace their path returning home.

Monarchs in the 39 states east of' the Rockies swarm toward isolated mountain ranges in Mexico. Roosting in large clumps, monarchs cover the trees in a blanket of orange and black -- a sight that may be familiar to those who live along the coast of California. Monarchs west of the Rockies forgo the trip to Mexico, content with the warm Pacific coast.

One thing naturalists struggle to understand is how the monarchs return to the same trees every year. Most monarchs die when they reach the central United States; it is actually their offspring that complete the journey.

Because monarchs need to reproduce along the migratory trail, it's important they find milkweed throughout the United States. A monarch will only lay eggs on milkweed, and their caterpillars will only feed on milkweed as well. Good news for the gardener and monarch, though, milkweed is hardy throughout most of North America and comes in a variety of stunning colors. Monarchs aren't simply picky creatures; while consuming milkweed, caterpillars ingest cardenolides, a substance that birds find very noxious. The cardenolides won't prevent a bird from snatching up a monarch, but after the bird becomes sick, it learns to leave monarchs alone in the future.

Due to development, the natural habitats of milkweed are slowly disappearing. Growing milkweed is an important way gardeners can assist monarch populations. Plant milkweed in large clumps in a sunny spot sheltered from the wind. Bushes with nectar-bearing flowers, such as lilac and butterfly bush, make excellent windbreaks and provide a source of food for adult butterflies. Milkweed, planted in conjunction with nectar-bearing flowers, aids monarch populations and attracts intriguing visitors to your yard.

Monarch Watch, a program managed by the Department of Entomology at the University of Kansas, offers special seed packs filled with 25 species of nectar-bearing plants. The package includes an instruction book with tips on garden design. To order, contact Monarch Watch at 888-TAGGING or www.monarchwatch.org.