Nation’s butterflies are disappearing at alarming rate, MSU researchers find

• Butterfly populations across the continental US have declined by 22% over the last two decades, according to a new national study
• It’s the latest indicator that human land development, pesticide use and climate change are fraying the base of the food web, with potentially dire consequences
• The findings should be a wake-up call, said authors, including two Michigan State University experts

The nation’s butterflies are disappearing at an alarming rate, a sign of a crisis in the insect world that could ripple throughout the food web, according to a new study co-authored by Michigan State University researchers.

The study, published Thursday in the journal Science, tallied two decades worth of data from more than 76,000 surveys of 554 butterfly species, revealing staggering population declines throughout the continental US.

Between 2000 and 2020, butterfly abundance plummeted by 22%. 

“This might be a bit of a canary in the coal mine for insect loss,” said Elise Zipkin, a Red Cedar Distinguished Professor of quantitative ecology at MSU who co-authored the paper with more than 30 researchers from across the country.

Zipkin attributed the losses to human impacts such as pesticide use, habitat loss and climate change. It’s the latest in a growing body of evidence that the world’s insects are disappearing, dangerously fraying the food web that connects all life on earth.

“For those who were not already aware of insect declines, this should be a wake-up call,” said Collin Edwards, the study’s lead author and a data scientist at the Washington Department of Fish and Wildlife, in a written statement. “We urgently need both local- and national-scale conservation efforts to support butterflies and other insects.”

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While alarming, the report’s findings may come as no surprise to backyard gardeners and butterfly enthusiasts. 

“My neighbors notice it,” read a statement from Nick Haddad, an MSU professor of integrated biology and co-author of the study. “Unprompted, they’ll say, ‘I’m seeing fewer butterflies in my garden; is that real?’ My neighbors are right.”

Migratory monarchs are a well-known example: The eastern population, which flutters through Michigan each summer, has plummeted by more than 90% since the 1990s.

Zipkin co-authored a 2021 study that found hot, dry weather caused by climate change to be a leading threat, alongside widespread pesticide use that has wiped out the milkweed populations where monarchs lay their eggs. 

Pesticides also kill insects directly, often seeping into the soil to produce harmful long-term effects.

Beloved by many for their beautiful colors and gentle flutter, butterflies are important plant pollinators, and a key food source for larger animals like birds and bats — both of which are experiencing their own precipitous declines.

One-hundred-and-seven of the butterfly species surveyed have lost more than half of their populations since 2000. The bright side, Zipkin said, is that they can reproduce prolifically under the right conditions. 

That means the declines are “not insurmountable”  — if individuals and policymakers choose to act.

Individuals can help address the problem by planting native plants in their yards, or restoring habitat in local parks. Policymakers need to get serious about addressing the overuse of pesticides, sprawling development that gobbles up butterfly habitat, and fossil fuel consumption that is driving climate change, Zipkin said.

“There are a couple of low-hanging fruits that would make a difference on a really big scale,” she said. “We could consider limiting the use of some types of pesticides, particularly neonicotinoids that have a large effect on insects.”

Several states have enacted laws to curtail neonicotinoid use, but not Michigan. Neonicotinoids are largely banned in Europe, but the US has not followed suit.