A new study finds the number of butterflies has dropped 22% since 2000, a new study finds
America’s Butterflies Are Disappearing at an Alarming Rate, Study Finds
WASHINGTON (AP) — The United States is experiencing a sharp decline in butterfly populations due to insecticides, climate change, and habitat loss, with numbers dropping by 22% since 2000, a new study reveals.
The study, published in Science, marks the first nationwide systematic analysis of butterfly abundance. It found that butterfly populations in the Lower 48 states have been decreasing at an average rate of 1.3% per year, with 114 species in significant decline and only nine showing an increase.
A Steady Decline With No Signs of Slowing
“Butterflies have been declining over the last 20 years,” said co-author Nick Haddad, an entomologist at Michigan State University. “And we don’t see any sign that that’s going to end.”
To reach these findings, scientists analyzed data from 35 monitoring programs, incorporating nearly 77,000 surveys that tracked a total of 12.6 million butterflies over several decades.
The results align with another alarming trend: monarch butterfly populations—currently being considered for the threatened species list—have plummeted to near-record lows, with fewer than 10,000 individuals counted last month. In 1997, there were 1.2 million.
Many butterfly species studied have declined by 40% or more.
‘Catastrophic and Saddening’ Loss Over Time
David Wagner, a University of Connecticut entomologist who was not involved in the study, praised its comprehensive scope. While an annual 1.3% decline may seem small, he emphasized that the long-term impact is devastating.
“In just 30 or 40 years, we’re talking about losing half the butterflies—and other insect life—across the continent,” Wagner said. “The tree of life is being denuded at unprecedented rates.”
The U.S. is home to approximately 650 butterfly species, but many are so rare they did not even appear in the data. Of those studied, 212 species were found in such low numbers that trends could not be accurately calculated, raising further concerns about their survival.
Vanishing Icons of Nature
Some of the best-known butterfly species have experienced dramatic declines. The red admiral—so docile it often lands on people—has dropped by 44%. The American lady butterfly, known for its distinctive eyespots, has fallen by 58%.
Even the invasive white cabbage butterfly, which has successfully spread worldwide, has seen a shocking 50% decline.
“How can that be?” Haddad wondered.
A Warning Sign for Humans
Cornell University butterfly expert Anurag Agrawal warned that butterfly loss could signal broader ecological dangers.
“The loss of butterflies, parrots, and porpoises is undoubtedly a bad sign for us and the ecosystems we depend on,” Agrawal said. “Butterflies are ambassadors for nature’s beauty, fragility, and interdependence. They have something to teach us.”
Beyond their aesthetic appeal, butterflies are vital pollinators. Though not as critical as bees, they play a key role in ecosystems, including the pollination of Texas’ cotton crops.
The Southwest is the Hardest Hit
The study found that butterfly declines are worst in the Southwest—Arizona, New Mexico, Texas, and Oklahoma—where populations have plummeted by more than 50% in just two decades.
“It looks like butterflies in dry and warm areas are doing particularly poorly,” said lead author Collin Edwards of the Washington Department of Fish and Wildlife.
Species that inhabit both northern and southern regions are faring better in cooler climates, suggesting that rising temperatures are a major factor in population loss.
The Role of Insecticides and Hope for Restoration
Climate change, habitat destruction, and insecticide use appear to be working together to weaken butterfly populations, the study suggests. While all three factors contribute, previous research indicates that insecticides may be the biggest culprit, particularly in the Midwest.
“It makes sense because insecticide use has changed dramatically since our study began,” Haddad said.
Despite the bleak findings, there is still hope. Butterfly populations can rebound if their habitats are restored.
“You can make changes in your backyard, in your neighborhood, and in your state,” Haddad said. “That could really improve the situation for a lot of species.”