Seven butterfly species found in Maine are experiencing some of the fastest population declines in the U.S.

These species, with fanciful names like Dreamy Duskywing and Coral Hairstreak, saw their population decline by more than half over two decades and some by more than 80%, according to a study published this month in Science. The findings are based on 12.6 million sightings observed by 35 monitoring programs from 2000 to 2020.

Some, like the Duskywing, remain common in Maine and have no special conservation status despite a steep 86% national decline over 20 years. Others, like the Hairstreak, whose national numbers fell 58%, are deemed locally imperiled, too, due to threats of habitat loss, pesticides and climate change.

“Butterflies play a critical ecological role, both as pollinators and as prey, but they can also tell us a lot about how development, pesticides and climate change are affecting the rest of the insect world,” said Collin Edwards, a Washington Department of Fish and Wildlife ecologist, the lead author of the study.

The study found about one in five U.S. butterflies, or 22%, have disappeared over the last 20 years. That works out to be a 1.3% decline each year.

Charlene Donahue, a retired entomologist with the Maine Forest Service, called the study’s findings worrisome. Butterflies are the “canaries in the coal mine” of the insect world, an indicator of what is happening to the less-beloved members of the invertebrate world and the environment in general.

“If butterflies aren’t doing well, there are a lot of other insects and habitats in trouble,” Donahue said.

Everybody loves butterflies, Edwards said. They can be beautiful or whimsical. Fans photograph, count and collect them. Their size makes them easy to spot and identify when compared with bees or fireflies. They are the most intensely observed and cataloged kind of insect on the planet.

As a result, butterflies get more funding set aside for their study and preservation than other insects. And because butterflies face the same existential threats as other insects, their condition can tell us what is going on with the rest of the insect world.

Despite the study’s grim findings, there is reason to hope, Edwards said. While only 3% of butterfly species showed population growth, butterflies have the potential to bounce back quickly with the right conservation efforts, such as habitat protection and pesticide protections, Edwards said.

“There is a lot of really depressing news in this report, but there’s also a lot we can do to protect butterflies, and some of the researchers who worked on this study have found those protections to be very successful,” Edwards said. “That’s the silver lining. A small one, but I’ll take it.”

The study does not claim to represent all butterflies — some parts of the country have a lot of observers, some none — but it measures the change in abundance of the butterflies in 2,500 survey areas revisited over 20 years. In Maine, the North American Butterfly Club conducted 48 surveys at five locations.

Maine doesn’t have a robust butterfly monitoring program that in other states provides a total butterfly count with species-by-species estimates. But in 2007, the Department of Inland Fisheries and Wildlife launched the Maine Butterfly Survey to fill in other information gaps for this beloved insect.

This program trained citizen scientists to fill information gaps on the distribution, flight seasons and habitat preferences for butterflies in the same way the department has done for bees and amphibians, said Phillip Demaynadier, who supervises the department’s wildlife diversity section.

Meant to last only five years, the survey continued for a decade and was turned into a regional guide — “Butterflies of Maine and the Canadian Maritime Provinces” — published in 2023. The survey helps the state decide which of Maine’s butterfly species are endangered, threatened or of special concern.

About 20% of the 120 butterfly species found in Maine have special conservation status, according to Demaynadier, one of the field guide’s authors. Many are listed because they are known to be losing their habitat, he said, not necessarily because scientists know if their population is decreasing.

But Maine biologists agree on the biggest threats facing local butterflies, especially elusive ones: loss or change of habitat, pesticides, invasive species and climate change, Demaynadier said. Aerial insecticide spraying to kill an introduced species like the spongy moth shows how such threats can multiply.

Scientists are still learning how climate change is affecting Maine’s butterflies, he said. Some butterflies like elfins and hairstreaks are starting to arrive in Maine earlier than in the past. Scientists worry about timing mismatches, with butterflies arriving before their host plants are ready to provide their nutrition.

Climate change is also threatening some of the cold-loving habitats that host rare Maine butterflies, like the alpine tundra favored by the endangered Katahdin Arctic and the boreal forests favored by Northern Blue, a species of special concern.

Herb Wilson, a retired Colby College biology professor who lives in Waterville, made four wet and buggy trips to the Saco heath before finding an endangered Hessel’s Hairstreak. In May 2014, he bushwhacked his way to a stand of the Atlantic white cedar that the endangered Hessel’s calls home.

After hours of beating the branches to get the butterflies out of the canopy, Wilson — who helped conduct the Maine Butterfly Survey — found himself 2 1/2 feet from a Hessel’s, easily recognizable by its telltale green wings with red stripes and white spots.

“The little rascal came down for nectar and I got some photographs of it perched on an open flower,” Wilson recalled. “I spotted an endangered Frigga Fritillary once, but a state biologist led me to it, which isn’t the same. This one I found entirely on my own. I floated back to my car.”

None of Maine’s eight threatened or endangered butterflies are represented in Edwards’ national study. Researchers didn’t have enough data on them to include, perhaps because Maine is at the southern edge of the species’ range. Some, like Maine’s Katahdin Arctic, can only be found in hard-to-reach areas.

But Maine believes another 13 butterflies are on the verge of becoming threatened or endangered, or what it calls species of special concern. Their low or declining numbers, limited distribution and special habitat needs mean the state wants to keep an eye on them, but it isn’t offering them any regulatory protections.

Two of these species deemed to be on the brink here in Maine, Leonard’s Skipper and Coral Hairstreak, experienced sharp national declines across all regions. Edwards’ study found that Leonard’s Skipper had declined by 84% and the Coral Hairstreak by 58%.

The Bronze Copper and Southern Cloudywing experienced 63% and 61% national declines, respectively. These are considered species of greatest conservation need, which means they are considered in need of voluntary conservation measures but not quite as badly as species of special concern.

The other three Maine butterflies that reported national declines greater than 50% include the European Skipper, the Dreamy Duskywing and Harris’ Checkerspot. The study concluded their national population numbers had declined by 92%, 86% and 77%, respectively, but they remain commonplace in Maine.

As an introduced species, the European Skipper is an unlikely candidate for additional local protections. But the Checkerspot’s wet meadows and marshes and Duskywing’s open meadow and streamside habitat could be protected if Maine wants to take steps to preserve the U.S. populations of these butterflies.

Retired endocrinologist Roger Rittmaster remembers walking through a colony of Harris’ Checkerspot in a meadow of flat-topped aster in Stockton Springs one June day a decade ago. He had only just moved to Maine and was in love with photographing butterflies, even the common ones.

He was struck by their beauty. The small bright orange butterflies have complex black markings, with an upper area that has spots, some with white centers, and an underwing with white bands divided by black lines. And where there is one, there are usually many, making them easier to photograph.

He returned a year later to gather caterpillars in the hope of starting a colony on his Camden property. He has documented 32 butterfly species in his backyard full of asters, but Rittmaster’s dream of building a backyard Checkerspot colony came to nothing. A handful of adults emerged, but they flew away.

“I tried several times to get people interested in doing butterfly counts, to establish a population baseline and annual surveys like the ones done in other states, but I couldn’t get enough people interested,” Rittmaster said. “Eventually I found all the butterflies I could reach and now I’ve moved on.”

Rittmaster, a board member of the Maine Entomological Society, now photographs flower flies.

Despite Maine’s apparent role as a national refugium for the Checkerspot and Duskywing, Maine law does not allow the state to add a species to its threatened or endangered species list unless it’s in trouble here, regardless of how poorly it might be doing elsewhere, Demaynadier said.

But the study’s findings could play a role when reviewing butterfly species of greatest conservation need.

The Xerces Society, an international nonprofit devoted to the study and protection of invertebrates and their habitats, plans to use the national study’s findings to develop conservation guides for policymakers and individuals to stem the tide of butterfly decline.

Maine’s official state butterfly, the Pink-edged Sulphur, appears to be doing fine. It was named the state butterfly in 2023 after two fifth graders from Old Orchard Beach petitioned the Legislature to honor the widespread butterfly as an important pollinator and wildlife food source.