Energy & Environment

Researchers say firefly populations are dying out due to human development, pesticides

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Researchers are warning that firefly populations are dying out and that human causes are to blame.

While catching lightning bugs is a favorite summer pastime for children, The Asbury Park Press in New Jersey reported Thursday that large-scale construction and development projects have decreased their marsh and wetland habitats, with further threats posed by the use of pesticides and weed killers.

While there is not yet quantitative data to determine population loss, entomologist Christopher Heckscher with Delaware State University told the newspaper that certain firefly species common several decades ago are now nowhere to be found.{mosads}

“I want my kids to be able to catch fireflies with their kids. Losing these things is not something that’s just going to affect us today but for the rest of time. I mean they’re going to be gone forever,” Hecksher said. 

Ben Pfeiffer, a master naturalist who founded, said he began to notice certain populations were disappearing near his home in south Texas back in 2008.

“It’s not just about a decline in terms of numbers. There’s a whole lot less firefly diversity than there used to be,” said Pfeiffer. “Some of the species are habitat-specific and when that habitat is gone, the species can be lost.” 

There are roughly 2,000 firefly species around the world, with 200 of those detectable in the U.S.

Lightning bug populations often reflect the environment around them, and while no one knows for sure what is causing population drops, researchers suspect light pollution is also to blame, the paper reported.

“They flash to signal for mates. Scientists believe they may flash to drive away predators, claim territory, and communicate with others of their species as well — although the finer points of their language have never been studied extensively,” according to “One thing’s for sure, though: without those flashing lights, there could be no fireflies.”

Pfeiffer’s website suggests turning off exterior lights in your garden or yard at night to help fireflies interact. 

Adult fireflies only survive for a few weeks and must mate during their short lifetimes. They spend up to a year in larvae form, eating slugs and snails while living on the ground.

Use of pesticides and weed killers in lawn care threaten their young forms, so limiting poisonous chemicals is another thing researchers say could help populations.

Tags fireflies Human development light pollution lightening bugs Pesticides
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