DELAWARE SHORE STATE PARK, Del. — On a muggy July evening, Delaware state biologist Jason Davis was doing what kids have always done: trying to catch fireflies.
It will never be as easy as the few summer nights of his own childhood, spent in this vast marshland between the bay and the Atlantic.
Davis sees the male’s double flash and gives chase; it flies in a zigzag pattern to the west. Davis follows; it flies in a zigzag pattern to the east. Davis says it seems the insect is toying with him. “I think it’s having fun.”
Finally, he flicks out a long net to catch what are called fireflies.
“That was four years of high school lacrosse,” he says.
The fireflies Davis chased, the Bethany Beach fireflies, are so rare that America’s first firefly Experts say it is expected to be placed on the endangered species list later this year.
Rising sea levels due to climate change and increased housing development are causing problems.
Davis and his colleagues estimate that fewer than 1,000 remain.
For many Americans, the flash of fireflies evokes childhood memories of summer nights gone by, but now they worry they’re gone.
Fireflies were once abundant, cool, easy to catch and observe, and served as a gateway to the natural world around us. But in recent years, entomologists have been hearing anecdotes about firefly population declines and worry that habitat loss, pesticides, light pollution, and climate change are fading their summer glow.
But the data was not there.And the most common firefly, nicknamed the “Big Dipper” for its swooping flight path, is thriving.The fireflies of many childhoods in the eastern and Midwestern U.S. “have weathered every challenge we’ve thrown at them,” says Sarah Lewis, a biologist and firefly expert at Tufts University.
But other species are also in trouble, and the Bethany Beach species is not the only one that is permanently at risk of extinction.
“They’re too important to lose, but too small for us to notice,” said Sergio Enriquez, invertebrate conservation coordinator at the Indianapolis Zoo, who is independently searching for a particular species of ghost firefly that hasn’t been seen in 35 years.
Fireflies are found in every state in the U.S. except Hawaii, and many different species emerge at different times of the night and summer.
They glow and blink in their own unique way, and while they can be hard to spot in urban areas without bright lights and plenty of habitat, scientists I created a map “We don’t know where to look,” said Candace Fallon, a conservation biologist with the Xerces Invertebrate Conservation Society.
A few years ago, scientists finally conducted a survey of the 170 species of fireflies recorded in the United States.
Or so they tried to do.
They focused on determining the health of 130 species, but “we found that we didn’t know enough about about 50 percent to make a guess. Some could be doing very well, others could be extinct,” Lewis said.
“We kind of took fireflies for granted for decades,” says Christopher Heckscher, a Delaware State University environmental science professor who in 1998 rediscovered the Bethany Beach fireflies after they had been lost for 30 years.
“Everyone assumes we know everything about them and we know every species and everyone loves them. They’re bioluminescent, which is really great. Kids love them. But it’s surprising how little we know about them.”
About a third of the 130 species surveyed in the United States and Canada are doing well, but about 18 are at risk, Fallon said.
Scientists say fireflies flash and blink to warn other creatures that they are too poisonous to eat, but they also flash to solicit mates. Males flash their appealing messages, and females respond. Each species has special light, color patterns and flight times that help identify them.
The average dipper is quite large for a firefly and emits a yellowish light.
“They fly by and then they start to glow and then they swoop and then they go up, it’s like they’re writing a J in the sky,” Lewis said. They’re a favorite with kids because they appear before dark and seem unaffected by light pollution.
But light pollution disrupts courtship behavior by turning off the males’ flashes, she says, which can reduce reproduction.
In Indiana, Enriquez has been keeping an eye on ghost fireflies, which have distinctive behavior that sets them apart from the Big Dipper. There are many different kinds of ghost fireflies, including the blue ghost firefly, which, despite its name, glows green.
Ghost fireflies move like ghosts.
“You’re in the dark, there’s nothing around you and then all of a sudden you see this long trail of green light moving slowly along the ground,” Henriquez said. “It was so spooky that it frightened their horses. Some people stopped to look and thought it was an alien or a UFO.”
The Smoky Mountains are home to a species of firefly called Photinus carolinus. They have become a tourist attraction because they tend to light up all at once.
Lewis said some fireflies, nicknamed femme fatales, mimic the light patterns of other species to attract males who they then kill and eat.
Climate change is another concern for fireflies, Lewis said, as prolonged droughts have hurt the insects in Europe and elsewhere, which often need wetlands, he said.
Davis believes rising sea levels due to climate change will eventually wipe out Bethany Beach’s firefly habitat.
But he and others believe that as people build homes in the few places where fireflies can live, they will be eradicated even faster.
Fireflies are special, Lewis said.
“Everyone loves fireflies, even people who don’t like insects. Some people don’t even realize they’re insects. They’re like little fairies,” Lewis says. “They’re the perfect ambassadors for the magic of nature.”
