Rare butterfly is flourishing - thanks to the US military

It's all down to how the US army manages its land - and that's just perfect for the frosted elfin.

A frosted elfin butterfly on a plant at the Fort McCoy Army Installation in Wisconsin. Tim Wilder/US army via AP)

BOSTON //  In the shadow of giant war machines, a tiny rare butterfly is flourishing. And hard though it may be to believe, experts say credit is due to the US military..

The frosted elfin, which flutters along on a tiny 2.5 centimeters wingspan, has found a home at several defence installations because of the way the military manages open spaces, said Robyn Niver, an endangered species biologist with the US Fish and Wildlife Service.

"Military training requires vast open areas, so these bases are some of our last great wild places," Ms Niver said.

Sightings of the little brown butterfly have been confirmed at Westover Air Reserve Base and Camp Edwards in Massachusetts; Fort McCoy in Wisconsin; Fort Bragg in North Carolina; and the New Hampshire State Military Reservation. The common thread among the bases is the way they manage vegetation through controlled burning, which creates the perfect conditions for wild blue lupine and indigo to grow - both host plants to the frosted elfin caterpillar.

The dainty butterflies were first spotted at Westover in Chicopee, Massachusetts, about 20 years ago, according to Jack Moriarty, the base's chief of environmental engineering.

Proper vegetation control is critical for the safety of the massive C5 military transport aircraft stationed at Westover. If the vegetation is cut too short, it attracts geese and gulls, increasing the risk of aircraft strikes. If it is allowed to grow too tall, turkeys, deer, and coyotes move in. Lupine and indigo are just the right height.

Although there have been anecdotal reports of its presence in the past, the frosted elfin was confirmed at Camp Edwards on Cape Cod only this  spring.

"It was pretty exciting. I was thrilled," said Jake McCumber,natural resources manager for the Massachusetts Army National Guard. "Our grasslands are in the headquarters area, so it's probably the busiest part of the base."

The area is used helicopter exercises and setting up field artillery equipmen.

Although they have been on the base for about 20 years, the frosted elfin population on the 24,300-hectares of Fort McCoy in Wisconsin appears to have exploded. About 130 of them were counted on the base this year, the highest number since the survey began in 2009.

Ms Niver said much could be learned about populations of other rare species which are thriving on military bases

"Our next step now is finding out how we can work with other partners besides the military to try to boost numbers of rare species on other lands as well," she  said.

Associated Press