The U.S. Fish and Wildlife Service has proposed that a rare firefly found near sand dunes on Maryland, Delaware and Virginia beaches be named a threatened species under the Endangered Species Act.

The insect is named the Bethany Beach firefly, because it was discovered in 1949 in the Delaware beach town, which is about seven miles north of Ocean City, Maryland.

It is the first firefly that the federal Wildlife Service has ever proposed for the endangered species list, and the service said it has been threatened by encroaching development along the seashore, climate change and other perils.

The story of the Bethany Beach firefly may mimic that of other beloved firefly species, best known for lighting up summer nights with their blinking glow. Thanks to habitat loss, light pollution and a warming globe, several species could be nearing extinction, according to a 2021 study that found that 14% of 132 firefly species in North America can be considered threatened with extinction.

Bethany Beach fireflies are distinctive from other similar species because of where they live, and their small size (less than half an inch long) and a black marking on their heads. They’re also known for a unique flash pattern, which they use to find a mate, involving two green flashes.

Up until 2020, when the fireflies were discovered on Maryland’s Assateague Island, they were known only to reside in freshwater wetlands in Delaware. Since then, the fireflies also have been discovered in Virginia at sites such as Chincoteague Island and NASA’s Wallops Flight Facility.

But their habitat has dwindled. The fireflies only live in highly specific, isolated habitats no more than 1,500 meters from shore, in freshwater marshes formed beside sand dunes thanks to rainwater and freshwater.

“These freshwater wetlands are pretty rare,” said Jess Tyler, a staff scientist with the Center for Biological Diversity in Arizona. “They’re only formed in dune ecosystems right along the coast. But of course, sandy beaches along the coast are very sought-after for development. So its habitat is likely way lower than it was a hundred years ago.”

These days, the populated marsh areas, called “swales,” are mostly located on undeveloped enclaves of shoreline in state parks, such as Fenwick Island State Park and Delaware Seashore State Park, according to the center. The two sites where a scientist first found the fireflies in Delaware have been lost to development. Another tract of private land in Bethany that hosted a sizable population of the fireflies was developed in 2019. Surveys after the construction haven’t turned up the fireflies, according to the center.

“The development was totally legal and permitted,” Tyler said. “The firefly was not protected at that point. But it potentially could be in the future.”

The nonprofit Center for Biological Diversity applied for endangered species protection for the firefly in 2019, and was grateful for Monday’s announcement, Tyler said.

“These dune systems have a lot of rare species that aren’t found in other areas,” he said, “and even though nobody really knew about this species before, it’s still important to protect — and it draws attention to the biodiversity of Maryland and Delaware and Virginia that maybe we didn’t appreciate before.”

Threatened status means that the agency has determined that the species is “likely to become endangered within the foreseeable future due to existing and emerging threats,” the Fish and Wildlife Service said in a news release.

In addition to development, the fireflies also face the threat of climate change. Rising sea levels could destroy their habitats. According to climate models cited by the Fish and Wildlife Service, somewhere between 76% and 95% of swales could be lost to high-tide flooding by 2100. The species also is impacted by pesticide use, light pollution, the encroachment of invasive plant species, and grazing by ponies, the service said.

The proposal to designate the firefly threatened, announced Monday, kicks off a public comment period lasting until Dec. 2, after which the service will make its final determination about the species’ endangered status. It usually takes about one year for a final determination after the initial proposal, said Bridget Macdonald, a Fish and Wildlife Service spokesperson.

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