The metamorphosis of a butterfly has forever been a useful metaphor for change and growth. But in recent years, butterflies have been linked with change in less poetic ways.
The number of butterflies in the U.S. decreased by 22% from 2000-2020, largely because of habitat loss, pesticide use, and climate change. This is the major finding of a 2025 study published in the journal Science that has been grabbing headlines lately.
“We brought together more than 12 million butterfly records from monitoring programs to understand the status and trends of butterflies across the United States,” says Eliza Grames, a Binghamton University biological sciences assistant professor who was one of the authors on the study. “I wish I could say the results were surprising, but the rate of decline we found was on par with estimated rates of decline for other insects in other parts of the world,” she adds. “We keep consistently seeing that insects are declining at about 1-2% per year.”
The study reported that on average, butterfly species in the northeastern U.S. are declining at an annual rate of about 1%. “I expect butterflies in New York would be declining at similar rates to the rest of the Northeast,” Grames says. Among the 20 species in the report that are declining the fastest, there are a few that can be found near the Hudson Valley: the West Virginia white, the European skipper, and the mottled duskywing. These are declining at rates of about 10-20% per year.
Also in early 2025, the World Wildlife Fund released what seemed to be a more optimistic report on Eastern monarch butterflies, which famously migrate to a mountain region in central Mexico each winter. During the 2024-25 winter season, those overwintering monarchs covered an area double the size of the previous winter, the report stated. But this is far from a comeback for the monarch. Single-year changes don’t necessarily reflect a shift in overall trends. “Even though the area covered by overwintering monarchs was more than the previous year,” Grames says, “it’s nothing even close to what it was five years ago, or even a decade or two before.”
Maraleen Manos-Jones has been a firsthand witness of the monarch’s decline. Manos-Jones is an environmental activist, educator, artist, author, and master gardener living in Ulster County, where she is well known for her butterfly gardens and advocacy on behalf of monarchs and other butterflies. In fact, since the late 1970s, she has traveled annually to Mexico’s Cerro Pelón mountain region, where she has helped document that site as a monarch overwintering location.
“When I first found the monarchs on Cerro Pelón in 1977, there were an estimated 100 million of them,” Manos-Jones recalls. “In 1978 and 1979, when I camped among the monarchs, they covered about 60 acres. By 2014 there were 3 million on one acre on Cerro Pelón. The following year, 6 million on two acres, and thus it has been fluctuating in that range, a fraction of what it once was.”
Because of the Eastern monarch’s disappearance, there is an ongoing campaign led by the U.S. Fish & Wildlife Service to have the butterfly federally listed as threatened under the Endangered Species Act. Manos-Jones has vigorously supported this cause.
Although the monarch is no exception to waning insect populations, there is a lesser-known butterfly species that has made remarkable progress, and it can be found not far from the Hudson Valley. “The Karner blue [butterfly] is a great example of a conservation success story,” Grames explains. “It’s a small, endangered butterfly that depends on pine barrens, which are a pretty uncommon habitat and require management like prescribed burns to maintain.”
Named after a hamlet midway between Albany and Schenectady, the Karner blue can be found in the nearby Albany Pine Bush Preserve, which is one of the world’s largest inland pine barrens. Interestingly, this species was first classified in 1943 by novelist Vladimir Nabokov, who spent time in this forest and was as passionate about the study and classification of butterflies as he was about literature.
Fortunately for the butterfly, and thanks in part to the advocacy of Nabokov and others, the Albany Pine Bush forest habitat is still intact today. “As a result of habitat restoration efforts, the Karner blue population in the Albany Pine Bush went from just a few hundred individuals in the early ’90s to there now being thousands of butterflies,” Grames says.
The Karner blue’s rebound can also be credited to restoration efforts in other places where the butterfly can be found, Manos-Jones points out. “In Wilton [N.Y.], the whole community got involved in planting wild blue lupines, which helped bring the Karner blue butterfly back from the brink of extinction,” she says, noting that monarch populations can benefit from similar community efforts to plant the milkweed that monarchs need for laying their eggs.
Local land conservation and habitat restoration can also help butterflies bounce back from impacts to changes in their climates. According to the authors of the Science study, they saw some of the biggest declines in areas of the country that are warming up fastest. But helping butterfly populations recover through habitat restoration is a way everyone can help address the declines.
“It is up to each and every one of us to help,” Manos-Jones says. “We cannot replace all the habitat that has been lost, but we can provide pesticide-free gardens to nourish the butterflies, birds, bees and bats. Our food system is reliant on them.”
