Species threatened by development
There are thousands of firefly species, but only one native to and named after a Delaware town. It’s the Bethany Beach firefly, and the U.S. Fish and Wildlife Service is one step closer to naming it an endangered species.
A petition was submitted to the service earlier this year by two nonprofits, the Center for Biological Diversity and the Xerces Society for Invertebrate Conservation.
“Based on imminent destruction of a significant portion of its range and degradation in the remaining portion, the Bethany Beach firefly is at immediate risk of extinction,” the petition states.
Dr. Tara Cornelisse is a senior scientist at the Center for Biological Diversity.
“I’m an entomologist and I’ve been studying insects, mostly beetles, most of my career,” she said. “The Bethany Beach firefly came up in my research as one that was very rare. A scientist in Delaware has already surveyed for it and written on it and said that it could really use federal protection, so that was a call to me. Xerces was also watching it closely.”
The Fish and Wildlife Service decided it warrants further study. It will begin gathering more information in the coming year to determine if it should be listed as endangered.
The Bethany Beach firefly is Delaware’s only endemic species. The bioluminescent beetle was first documented in 1949.
Its habitat is Sussex County’s freshwater swales between the dunes. These swales have always been few and fragile, dependent on the weather. Combined with other factors, these habitats are now so few that the Bethany Beach firefly has been found in only seven specific places, six within state parks at Cape Henlopen, Delaware Seashore and Fenwick Island. The seventh, home to the largest population, is within the Tower Shores Beach Community in the Breakwater Beach development, north of Bethany Beach.
Like most fireflies, the Bethany Beach firefly is nocturnal. It is recognizable by two bright green flashes, emitted by males in search of mates. Females will flash back in response but also to lure in other species of fireflies, which they eat. By eating other fireflies, the females ingest and pass onto offspring a toxin that protects them from prey by making them unpalatable.
Bethany Beach firefly larvae live up to two years in the soil, eating worms, snails and slugs. Adults live for a few weeks. They are weak flyers and do not often travel outside their particular swale habitat.
A species in danger
The Center for Biological Diversity and the Xerces Society’s petition names major factors that are endangering the Bethany Beach firefly: urbanization, climate change, insecticides and invasive plants, to name a few.
Sussex County’s coastal areas have had an 82% population increase since 1980, according to 2017 U.S. Census Bureau estimates. Virtually all of the beachfront land has been developed, save for those within state parks, meaning much of the Bethany Beach firefly’s habitat has been destroyed.
Urbanization causes other dangers, like habitat fragmentation, light pollution and human recreation.
The petition cited the 2018 Intergovernmental Panel on Climate Change when it connected the loss of the Bethany Beach firefly’s habitat with climate change. Human activities have increased the global average temperature, which has resulted in sea level rise and an increase in severe weather, and therefore a loss of certain ecosystems, like interdunal freshwater swales.
Mosquito spraying is affecting the Bethany Beach firefly, too. The firefly’s habitat is a home to mosquitoes and sprayed by the Delaware Mosquito Control Section. According to the petition, mosquito spraying often affects adult fireflies because it’s done when they’re most active -- at dusk or at night.
Freshwater swales can easily fall victim to nonnative plants. In particular, a dense stand of common reed can quickly crowd out other vegetation. It provides little nutrition or shelter to insects and animals.
Help for fireflies
The Bethany Beach firefly is already listed as endangered by the Division of Fish and Wildlife, but that gives no tangible protection. By listing the Bethany Beach firefly as endangered under the federal Endangered Species Act, its habitat would be protected by restrictions on things like development and pesticides. Population decline would also be mitigated by efforts to monitor and manage it.
“Despite knowledge of the perilous state of this firefly the Delaware state endangered species program and state park management plans do not provide any significant or species specific regulations regarding the conservation of the Bethany Beach firefly,” states the petition. “The only adequate regulatory mechanism available to save the Bethany Beach firefly starts with listing it under [the Endangered Species Act].”
“Basically, that means any activities that are going to put the species in jeopardy will need to be evaluated by Fish and Wildlife and approved, altered or halted altogether,” Cornelisse said. “In addition the species will receive recovery plan and that is really crucial because it lays out steps in the best available science that show us how we can augment the species and its habitat.”
The Center for Biological Diversity and the Xerces Society urged U.S. Fish and Wildlife to designate the firefly’s habitat as a “critical habitat,” which can require “special management considerations and protections.”
The U.S. Fish and Wildlife Foundation declined to protect the Bethany Beach firefly on an emergency basis, as the petition requested. They did commit to next steps in determining whether or not to list it as a threatened or endangered species.
In conjunction with U.S., the state Division of Fish and Wildlife conducted a preliminary survey earlier this year.
“They actually did some surveys this past summer and found that it was indeed very rare,” said Cornelisse. “Next, what they do is what’s called a species status assessment and that’s more in-depth.”
By law, the assessment is supposed to take no more than a year. However, the review of the petition was supposed to take no more than 90 days and it took almost six months.
“The emergency petition, it doesn’t have much of a legal hook, but it says, ‘Hey, look at this sooner than later because this species is really, critically in peril,’” Cornelisse said. “Usually it takes several years. Even ten or 12 or longer.”
A lot of what they do at the Center for Biological Diversity, she added, is sue U.S. Fish and Wildlife for inaction.
“It’s a big problem and something we’re constantly monitoring,” she said.