Fewer monarch butterflies expected in Missouri this fall

ST. LOUIS — Scientists are reporting a significant drop in monarch butterfly migration numbers for the 2024 fall season, with sightings expected to be rarer this September and October. This development adds to the ongoing concerns about the future of the species and its remarkable annual journey.

Population drop

The Missouri Botanical Garden reports that during the 2023-2024 overwintering period, researchers observed a 59% decrease in the monarch population compared to the previous year. The number of butterflies surviving the trip to Mexico was the second smallest overwintering population ever recorded. Researchers attribute the sharp decline to habitat loss and climate change, which have reduced the number of suitable resting places for monarchs during their migration.

Tad Yankoski, senior entomologist at the Sophia M. Sachs Butterfly House, commented on the situation: “The numbers have been fluctuating so much over the last couple of decades that, although I was not expecting this news, I am also not incredibly surprised to hear it either. This reinforces how important it is to act swiftly to protect migrating Monarchs while we still can.”

Monarchs are currently considered a vulnerable species, a status updated in December 2023. While not listed under the Endangered Species Act , the U.S. Fish and Wildlife Service (USFWS) is re-evaluating the monarch’s status. Many experts anticipate a potential proposal to add monarchs to the list of protected species by the end of the year.

An epic migration

Eastern North American monarchs undertake a several-thousand-mile journey from Canada to central Mexico each year . They travel during daylight hours and rest at night, often in pine, fir, and cedar trees. Remarkably, the monarchs making this journey have never been to their destination before, relying on inherited instincts to guide them.

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

Conservation efforts also focus on preserving and restoring milkweed plants, which are essential for monarch reproduction, and protecting their wintering grounds in Mexico.

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