Wild blue lupine is found in pine barrens and sandy areas in the eastern U.S. This area at Westover Air Reserve Base is managed to keep it open and encourage the rare wild plant to return year after year. Credit: Leah Hawthorn/USFWS

Four people moved slowly through seven acres of blue wildflowers at the Westover Air Reserve Base in Chicopee, Massachusetts. The nation’s largest Air Force Reserve base, Westover has supported missions like the direction of Patriot missile-defense batteries to Turkey and the response to Hurricane Sandy on the U.S. East Coast in 2012.

Today’s mission on the airfield was closer to home, much smaller (some might even say dainty) and by no means threatening. We were on the hunt for a butterfly — not the striking monarch, but the unassuming frosted elfin, whose brown wings span just about one inch.

Frosted elfin
Frosted elfin
A frosted elfin at Fort McCoy in western Wisconsin. Can you see its single tail on the hindwing? Credit: Tim Wilder

Birders discovered the rare butterfly on base about two decades ago. Why might the frosted elfin find its way to Westover? To make its home in the wild blue lupine, one of only two flowers that frosted elfin caterpillars can eat.

And why would a rare flower survive on an air reserve base with heavy training activity? Turns out that the lupine — and therefore the butterflies — love it.

The frosted elfin has been recorded in the grassy savannas of at least five Department of Defense installations within its eastern U.S. range. Each uses prescribed burns to maintain grasslands, prevent wildfires and reduce invasive plants while training firefighters. The burns reset the clock, as Native Americans and nature once did, creating ideal conditions in barrens for shade-intolerant plants like wild lupine and indigo.

The burns are especially important at Westover, said Jack Moriarty, the base’s environmental flight chief.

“Westover Air Reserve Base has the biggest contiguous grassland in New England,” Moriarty said. “The prescribed burns reduce fire hazards. They are good for the airfield, good for the birds and good for the grasslands.”

Jack Moriarty
Jack Moriarty
Jack Moriarty, Westover Air Reserve Base environmental flight chief, stands in lupine on the airfield. Credit: Leah Hawthorn/USFWS

The frosted elfin is already protected by multiple state wildlife agencies, has been completely lost in several other states, and is at risk of needing federal Endangered Species Act protection. The U.S. Fish and Wildlife Service has identified the elfin as a species for which quick, thorough and effective conservation action could restore butterfly populations and possibly prevent the need for that protection. The agency must decide by September 2023 whether the frosted elfin is threatened or endangered, or neither.

As barrens and savannas have been developed or allowed to overgrow, pockets of wild lupine and indigo have disappeared from many areas where the frosted elfin once flew.

“If we can get people engaged and committed to managing habitats for the frosted elfin, we might be able to put the butterfly back on the right path,” said Robyn Niver, a Service endangered species biologist. “The Department of Defense is well-positioned to play a critical role in restoring the frosted elfin.”

Congress, through the Sikes Act of 1960, recognized that military lands contain some of the nation’s most valuable natural resources. The act requires DoD installations to have plans outlining how their activities align with managing those resources. Take a look at the plan for Camp Edwards on Cape Cod, and you’ll find that carefully planned prescribed burns and selective tree cutting and herbicides benefit an entire community of wildlife that depend on the pine barrens, including the at-risk New England cottontail.

“The Department of Defense and our military are some of our most effective land stewards,” said Jake McCumber, natural resources program manager for the Massachusetts Army National Guard. “At most DoD bases, work needs to be done to sustain training lands, and that happens to be the same work needed to conserve these ecosystems and dependent species.”

“There’s a beautiful continuity to it.”

The elfin had flown under McCumber’s figurative radar until this past May, when he confirmed its presence in an Edwards savanna. He was hardly surprised: The base for years had been managed to benefit species with needs similar to those of the small flier. The site is also home to prairie warblers, field sparrows, clay colored sparrows and merlins.

(L-R) Frosted elfin at Ft. McCoy by Tim Wilder, frosted elfin caterpillar and frosted elfin at Concord State Military Reservation by Arin Mills

The elfins appear to be in the right place, if others species’ success in other areas of Camp Edwards is an indicator. While populations of scarlet tanagers and brown thrashers are dropping drastically in some areas, they’ve steadily increased at Camp Edwards. The trend shows promise for managing pine barrens for training and a variety of habitats.

The species is spreading its wings elsewhere, too. At Fort McCoy in western Wisconsin and at Concord State Military Reservation in southern New Hampshire, frosted elfins have become easier to find during the few spring weeks between when they emerge from cocoons under the lupine and when they mate and lay eggs on those plants. The elfins have benefitted from work targeted to benefit the endangered Karner blue butterfly, which also relies on lupine.

“It has been good to see the increase in frosted elfins over my 10 years here,” said Arin Mills, a New Hampshire Army National Guard conservation specialist. “Where at one time it may have been more of a treat, we go out on a butterfly survey during the expected flight time and almost always see a frosted elfin here on the State Military Reservation.”

At Fort McCoy, frosted elfin observations have jumped higher every year since targeted surveys began in 2009. This year, searchers counted more than 100 — — triple the 2016 tally.

Tim Wilder, an Army endangered species biologist, wonders why he hasn’t seen them in more places on base. Lupine covers 3,000 acres there, but frosted elfins aren’t using all of it. Nonetheless, it’s home to other species, including the phlox moth, dreamy duskywing, and Henry’s elfin.

Tim Wilder points out frosted elfin
Tim Wilder points out frosted elfin
Tim Wilder, an Army endangered species biologist at Fort McCoy, points out a female frosted elfin preparing to lay eggs. Photo courtesy of Tim Wilder

“The area where we observe our highest numbers of frosted elfin butterflies has been used for some level of military training for over 70 years,” Wilder said. “These rare species, including the frosted elfin butterfly, are still found on Fort McCoy, at least in part, because of the military training and other land management activities that have occurred on the landscape over the past 100-plus years.”

Department of Defense installations like Fort McCoy are coordinating with the Service to better understand where the species still occurs, and the kind of conservation efforts that will best help it succeed. Niver, the Service’s endangered species biologist, said the agency will develop a conservation strategy to guide future surveys, research, and management efforts.

Little copper butterfly
Little copper butterfly
NOT a frosted elfin. One of several American copper butterflies seen at Westover Air Reserve Base during our May visit. Credit: USFWS

On that cool morning in May at Westover, we admired the striking blue blooms that bubbled up the lupine stem. We watched moths, bees and American copper butterflies buzz or bounce from plant to plant. Frosted elfins were nowhere to be found.

The butterfly’s flight was over, but it would be back next year.

Conserving the Nature of the Northeast

We conserve nature in the northeast U.S. for the benefit of wildlife and the American people. Love your natural and wild places! Explore the world around you by hiking, fishing, hunting, and volunteering. More info at

U.S. Fish & Wildlife Service Northeast Region

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Conserving wildlife and habitats from Maine to Virginia, New York, and Pennsylvania.

Conserving the Nature of the Northeast

We conserve nature in the northeast U.S. for the benefit of wildlife and the American people. Love your natural and wild places! Explore the world around you by hiking, fishing, hunting, and volunteering. More info at

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