Here's How We Are Killing Off the Fireflies

©. Fireflies flying in forest at dusk, Prachin Buri, Thailand. (Photo: Peera_stockfoto / Shutterstock)

Serious threats are endangering lightning bugs across the globe; and they are all thanks to humans.

I grew up in California, a place where fireflies lack the ability to light up. During summer visits to my grandmother's lake house in the midwest, I was so deliriously enchanted by the magic of these glowing fairy insects that I cursed my home state for producing such duds. Is there anything more iconic of a summer evening than the show of flashing lights performed by a firefly?

Whenever I write about fireflies, commenters note that they are seeing fewer and fewer of these glowing wonders. Is it just anecdotal? Sadly, no. The scientific and citizen consensus agree that all is not well for the fireflies. There is even an international symposium of experts dedicated to conservation of the firefly. “Scientists have for years been warning that the world’s estimated 2,000 species of fireflies are dwindling, notes " The New York Times.

Now researchers from Tufts University and the International Union for the Conservation of Nature have taken a closer look to better understand the state of the fireflies. They surveyed firefly experts around the world to determine the biggest threats to survival for their local species.

According to the survey, habitat loss is the most prominent threat to firefly survival in most geographic regions, followed by light pollution and pesticide use. The ol' insect extinction trifecta.

"Habitat loss, pesticide use and, surprisingly, artificial light are the three most serious threats endangering fireflies across the globe, raising the spectre of extinction for certain species and related impacts on biodiversity and ecotourism," according to Tufts.

"Lots of wildlife species are declining because their habitat is shrinking," said Sara Lewis, lead researcher and professor of biology at Tufts University, "so it wasn't a huge surprise that habitat loss was considered the biggest threat. Some fireflies get hit especially hard when their habitat disappears because they need special conditions to complete their life cycle."

They explain that, for instance, the Malaysian firefly (Pteroptyx tener) – which is famous for its synchronized flashing, is a "mangrove specialist." Previous research has shown dramatic losses in this species after mangrove habitat was converted into palm oil plantations and aquaculture farms.

female firefly
A female glow-worm (Lampyris noctiluca

© Jason Steel

Second on the list of threats is light pollution. Given that many fireflies rely on their namesake fire to find mates, illuminating the night with artificial light wreaks havoc on the insects' love life.

"In addition to disrupting natural biorhythms – including our own – light pollution really messes up firefly mating rituals," explained Avalon Owens, Ph.D. candidate in biology at Tufts and a co-author on the study.

And perhaps it's no surprise that the widespread agricultural use of pesticides is another strike against fireflies. Pesticides are created to kill insects, and kill they do ... even the good guys, like fireflies and important pollinators.

While this is all so depressing – humans strike again, yay us – it is also hopefully hopeful that scientists are rallying around the fireflies of the world. And by determining what the risks are, the researchers will be able to better predict which populations are vulnerable to what.

For example, females of the Appalachian blue ghost firefly (Phausis reticulata) are not able to fly. "So when their habitat disappears, they can't just pick up and move somewhere else," explains co-author J. Michael Reed, professor of biology at Tufts.

"Our goal is to make this knowledge available for land managers, policy makers, and firefly fans everywhere," said co-author Sonny Wong of the Malaysian Nature Society. "We want to keep fireflies lighting up our nights for a long, long time."

The paper “A Global Perspective on Firefly Extinction Threats” was published in the journal Bioscience.