Searching for fireflies at the Delaware beaches: Why a biologist is looking for the rarest of all

Maddy Lauria
The News Journal

On warm summer nights one of Jason Davis’ favorite things to do is to watch his 5-year-old run around their backyard in Rehoboth, gleefully scooping up fireflies with a net.

This summer, after his little ones are tucked away for the night, it’s Davis’ turn to take out his net.

He travels further afield, to some of the most unique wetlands along Delaware’s beaches to search for one of the world’s rarest fireflies.

His searches are the first time in about two decades that anyone has really looked for Photuris bethaniensis, commonly known as the Bethany Beach firefly.

“We want to find out if [they still survive] in the state,” said Davis, a wildlife biologist with the Delaware Department of Natural Resources and Environmental Control. “Then we can protect them.”

Jason Davis, a wildlife biologist with the Delaware Department of Natural Resources and Environmental Control, tries to determine if he caught a rare Bethany Beach firefly.

Davis’ quest to revisit the firefly’s existence coincides with national conservation groups petitioning the federal government to get the beetle emergency protections under the Endangered Species Act.

That petition came after news broke of a developer building a massive boardwalk road to multimillion-dollar houses on top of one of the firefly’s most abundant wetland homes north of Bethany Beach.

DEVELOPMENT THREAT:New beach development could help kill off rare Bethany Beach firefly, only seen in Delaware

Wood shavings and tree stumps can be seen along the edges of the boardwalk that will serve as a road connection lots that average about $1 million in a private community north of Bethany Beach.
An aerial photo taken Tuesday, July 16, 2019, in Bethany Beach, Del., shows a wooden road built on pilings in one of the freshwater wetlands in coastal Delaware where the Bethany Beach firefly, which some environmentalists want added to the federal Endangered Species List, has been previously found.

Davis, who also is working to survey the state's other rare insects and bees, had planned to search for the Bethany Beach firefly before the petition was announced.

It's been so long since anyone took a close look at where these fireflies are — and how many are left — that it was hard to say how development would impact the fate of this symbol of summer known for its distinctive, double green blinking pattern.

First, the good news: Not only has Davis found fireflies in six locations where they were once found 20 years ago, but they also may be living in up to eight other sites along Delaware’s coast.

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The bad news: The number of fireflies he’s seen has not been impressive. At most, he’s found groups of 20 to 30 Bethany Beach fireflies flitting around a wetland. That’s far fewer than the 100 or so documented at some coastal sites in the early 2000s.

“The abundance we’ve seen is pretty low,” he said as he waited for the sun to set on Delaware Seashore State Park in late July. “In most wetlands we’re seeing only one or two.”

Counting every Bethany Beach firefly is not Davis’ immediate goal. For now, with the help of several others from the U.S. Fish & Wildlife Service, he’s trying to find out where they are so the state can decide how to protect their habitats.

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A Bethany Beach Firefly.

He has to be quick and quiet in his quest because he suspects the Bethany Beach firefly can sense when he's on the hunt.

As male fireflies double-blink to the females hiding in the brush as dark sets in and the mosquitoes emerge, Davis foregoes bug spray, in case the chemicals chase the fireflies away, too. That's a challenge in itself.

Even being out in the dark until midnight or 1 a.m., it's no surprise that these high-flying beetles are hard to catch, especially when his years of insect netting were practiced in the daylight. It can take hours to capture that tiny trail of light plummeting to the ground.

In areas that have at least three or four other species of fireflies that also glow a fluorescent-green hue, any lighting source can play tricks on the eyes in the dark. Airplanes flying by and blinking can be mistaken for a firefly at first glance, distracting Davis’ search while the real fireflies fly high above the trees and phragmites.

Jason Davis, a wildlife biologist in Delaware, is on a mission to find out where surviving Bethany Beach fireflies are found.

Phragmites, an invasive coastal plant, may be the largest threat to the firefly. Or maybe not. This plant can swallow entire wetland areas by pushing out native plant species, but it’s unclear whether this firefly species has adapted, Davis said.

In addition to development and invasive species wreaking havoc on their habitats, the firefly also is threatened by sea level rise.

Because they depend on specific freshwater wetlands called interdunal swales, saltwater threatens to destroy those habitats as well, state and national experts previously said.

“People need to see what we have and how vulnerable it is to being lost,” Davis said of the firefly. “Maybe one day people can come and enjoy the sunset on the beach and then wait for this.”

Is there another threatened species in Delaware that needs to be investigated? Contact reporter Maddy Lauria at (302) 345-0608, mlauria@delawareonline.com or on Twitter @MaddyinMilford.