Light pollution is major threat to NC's diverse firefly population, scientists say

When you think back on your summers as a child, you may remember catching fireflies at dusk. While fireflies are a summer staple for many children, research shows that human activity could cause North Carolina's diverse firefly population to dwindle if action is not taken to preserve them.

Posted 12:42 p.m. Jun 16, 2022 — Updated 1:37 p.m. Jun 16, 2022

Maggie Brown

, WRAL mutliplatform producer

RALEIGH, N.C. — When you think back on your summers as a child, you may remember catching fireflies at dusk. While fireflies are a summer staple for many children, research shows that human activity could cause North Carolina's diverse firefly population to dwindle if action is not taken to preserve them.

Clyde Sorenson, an entomologist at North Carolina State University, says that the biggest threat to fireflies is light pollution and inappropriate pesticide use. Fireflies use the darkness to communicate, and without it, they aren't able to reproduce as much.

"If there's too much ambient light around, it could alter the behavior of the insects," Sorenson said.

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North Carolina has a diverse population of fireflies — in the mountains and in coastal areas — all are threatened in unique ways.

"When compared to many other places, we have a pretty high diversity of fireflies," he said. "Ecologically, they are important."

Fireflies spend most of their life as larva, preying on slugs and earthworms in the soil. If there are fewer predators for those insects in an environment, then slugs and earthworms can overrun crops.

"It can alter the ecological balance in those habitats," he said. "But beyond that, fireflies are just fascinating because of the mystery of their displays."

A study released last year found that fireflies across North America are at-risk of extinction, particularly in South Carolina and Florida. Many fireflies live near marshes and wetlands, and as those habitats are threatened, so are fireflies.

"There's legitimate reason for concern," Sorenson said.

For many species of fireflies, females are flightless, so they are not easily able to relocate if their habitat is lost.

Sorenson said there's not many people who've invested time and resources into studying fireflies.

"We need to make sure we understand who we have and where they live," he said. "We need to put more effort into identifying populations of particularly the rarer species of fireflies. And then one of the post important things we can do is protect those habitats of degradation."

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