A recent study has revealed concerning data regarding the decline of butterfly populations in the United States. Between 2000 and 2020, total butterfly abundance decreased by 22% across 554 recorded species, with data drawn from over 76,000 surveys and 35 monitoring programs.
The research, which gathered 12.6 million butterfly records, paints a grim picture of the widespread decline of these vital insects. While butterflies are one of the most surveyed insect groups, previous studies have either been geographically limited or relied on data from a single monitoring program.
Of the species recorded, declines were far more common than increases, with 13 times as many species experiencing declines in their populations. This decline was seen across the entire contiguous United States, indicating that the issue is not isolated but widespread. Experts stress that the consequences of losing butterfly populations could be dire, as they play critical roles in ecosystems, including pollination and food chains.
“Butterflies have been declining the last 20 years,” study co-author Nick Haddad, an entomologist at Michigan State University told The New York Post. “And we don’t see any sign that that’s going to end.”
David Wagner, a University of Connecticut entomologist who wasn’t part of the study, praised its scope. And he said while the annual rate of decline may not sound significant, it is “catastrophic and saddening” when compounded over time.
“In just 30 or 40 years we are talking about losing half the butterflies (and other insect life) over a continent!” Wagner said in an email.
“The tree of life is being denuded at unprecedented rates.”
Butterfly decline as a warning sign for humans
Cornell University butterfly expert Anurag Agrawal told NYPost that he worries most about the future of a different species: Humans.
“The loss of butterflies, parrots and porpoises is undoubtedly a bad sign for us, the ecosystems we need and the nature we enjoy,” Agrawal, who wasn’t part of the study, said in an email.
“They are telling us that our continent’s health is not doing so well … Butterflies are an ambassador for nature’s beauty, fragility and the interdependence of species. They have something to teach us.”
Oberhauser said butterflies connect people with nature and that “calms us down, makes us healthier and happier and promotes learning.”
What’s happening to butterflies in the United States is probably happening to other, less-studied insects across the continent and world, Wagner said.