When to expect the monarch butterfly migration in Missouri

ST. LOUIS — September is here and that means monarch butterflies begin their remarkable migration through Missouri , heading towards their winter homes in Mexico. This year, the peak in monarch numbers seems to be occurring later than usual in many Midwestern states . While some monarchs have already begun their southward journey, many observers are still seeing eggs and caterpillars, even in northern areas . While the sight of these migrating butterflies is still common, continued habitat loss threatens the future of this natural phenomenon.

Monarch butterflies are currently considered a vulnerable species . This status, updated in December 2023, reflects ongoing concerns about their population. While not as severe as their previous “endangered” classification, the change doesn’t indicate an improvement in monarch numbers. Instead, it results from a different method of assessing their population over the past decade.

Eastern North American monarchs travel south from Canada to central Mexico each year . They fly during daylight hours and rest at night, often choosing pine, fir, and cedar trees for their evening stops. These trees provide suitable shelter from the elements.

The butterflies eventually gather in specific mountain areas in Mexico, where they spend the winter months. Remarkably, the monarchs making this journey have never been to these locations before, relying on inherited instincts to guide them.

The monarch population has been declining for several decades. This decrease is largely due to loss of habitat both in North America and Mexico. In North America, the reduction of milkweed plants, which monarchs need to lay their eggs, has been particularly harmful. The loss of nectar-producing plants that fuel their journey south has contributed to their struggles. In Mexico, the clearing of trees in their wintering grounds poses another significant threat.

To help monarchs during their migration, consider planting flowers that bloom in late summer and fall. Native perennials such as asters, goldenrod, and ironweed are particularly beneficial. These plants provide nectar that helps fuel the butterflies on their long journey. They also support other pollinators like bees and different butterfly species.

Note: The video in this report is from September, 2023.

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