Butterflies are vanishing across the United States at an alarming rate, prompting urgent warnings from scientists. A groundbreaking study published in Science analyzed data from over 76,000 surveys nationwide and found that butterfly populations declined by 22% between 2000 and 2020.
For every five butterflies fluttering in the year 2000, only four remained two decades later.
“Action must be taken,” urged Elise Zipkin, a Red Cedar Distinguished Professor of quantitative ecology at Michigan State University (MSU) and a co-author of the study. “Losing 22% of butterflies across the continental U.S. in just two decades is distressing and highlights the need for large-scale conservation efforts.”
THE SCIENCE BEHIND THE CRISIS
Zipkin and her MSU colleague, co-author Nick Haddad, have been at the forefront of butterfly research. Zipkin analyzes vast data sets to track ecological trends. While Haddad, a terrestrial ecologist, studies the most vulnerable butterfly populations firsthand.
Their findings are worrying. Using records from 35 monitoring programs that tracked over 12.6 million butterflies, the team found that butterfly populations are shrinking at an average annual rate of 1.3%. The Pacific Northwest showed an apparent 10% increase in abundance. Scientists attribute this largely to a temporary population boom of the California tortoiseshell butterfly.
“My neighbors have noticed it,” Haddad said. “Unprompted, they’ll ask, ‘I’m seeing fewer butterflies in my garden— is that real?’ And the answer is yes. It’s shocking.”
THE BIGGER PICTURE: A BIODIVERSITY CRISIS
The study revealed that for every species of butterfly that increased in numbers, 13 species declined. A staggering 107 species lost more than half their populations in just 20 years.
Butterflies are more than just beautiful insects—they play a crucial role in ecosystems. They help recycle nutrients and serve as a key food source for birds and other wildlife. Alarmingly, their population decline mirrors the loss of nearly 3 billion birds in North America over the past 50 years.
“People often think of bees as primary pollinators, but butterflies also play a vital role,” Zipkin explained. “For example, in Texas, butterflies contribute to $120 million worth of cotton production.”
THE ROLE OF POLICY AND CONSERVATION
Zipkin sees this study as a wake-up call for policymakers.
“We depend on biodiversity for clean air, water, and food,” she said. “Yet, species loss is occurring at rates comparable to major mass extinction events. The U.S. government must take responsibility for ensuring future generations have the resources they need.”
Haddad’s recent research, published in PLOS ONE, found that insecticides pose a greater threat to butterflies. This threat is more significant than habitat loss or climate change. He argues that conservation efforts should focus on smarter land management rather than excessive pesticide use.
“Overuse of insecticides is harming butterflies and other beneficial insects with no proven benefit to crop yield,” Haddad warned. “Reducing unnecessary pesticide use and restoring underperforming farmland to natural habitats could help butterflies recover.”
A CALL TO ACTION
Despite the grim statistics, scientists believe there is hope. By implementing conservation strategies, reducing pesticide use, and protecting natural habitats, butterfly populations could rebound.
“The widespread application of insecticides can be reversed,” Haddad said. “If we take action now, butterflies and other pollinators will recover.”
This urgent study, titled “Rapid Butterfly Declines Across the United States During the 21st Century,” was authored by a team of experts from multiple institutions. These include Michigan State University, Washington State University, and the University of Nevada.
The future of butterflies—and the ecosystems they support—depends on immediate action.