March 17, 2025
Butterflies play a critical role in several ecological processes, including serving as an important food source for birds and as pollinators for crops. The bad news is that they’re disappearing – fast.
Ecologists have long known that butterfly populations were decreasing as they faced threats from climate change, pesticide use, and other stressors. The fragmented nature of data collection across broad geographies and hundreds of species, however, meant that getting a clear picture of the issue at scale was difficult. New research, funded in part by the Midwest Climate Adaptation Science Center (MW CASC), offers the most comprehensive look yet at the situation and demonstrates the magnitude of the problem.
After collecting and analyzing data from nearly 77,000 surveys from across the U.S., the researchers found that total butterfly abundance fell by 22% across the more than 550 recorded species over a 20-year period. Some species faced steeper declines than others, with about half of the species analyzed in this study experiencing population drops of 42% or more.
The authors call these findings a wake-up call for anyone not yet aware of the population declines of butterflies and other insects. Elise Zipkin, a member of the research team, told MSU Today, “To lose 22% of butterflies across the continental U.S. in just two decades is distressing and shows a clear need for broad-scale conservation interventions.”
While these findings paint a grim picture, there may be hope. The researchers point to habitat conservation and more strategic use of insecticides as important actions to slow and prevent future population losses. For specific highly threatened species, managed relocation and genetic rescue may also be impactful strategies. “Butterflies have the potential for rapid population growth under the right circumstances,” the authors write. With the right management actions, we have the opportunity to build a future where butterflies and the ecosystems that rely on them thrive.