Few sights induce nostalgia like the flickering glow of fireflies at night.
But these beloved, bioluminescent insects, also known as lightning bugs, are in trouble. Their populations are declining around the world as the threats against them pile up. In the U.S., 18 species face extinction—and experts say global species are endangered too.
“Do you want to live in a world where this experience is lost to your grandchildren?” says Sara Lewis, co-chair of the International Union for Conservation of Nature’s Firefly Specialist Group.
You might not have to. Here’s what you can do to ensure that fireflies will continue to light up our backyards for generations to come.
Create a firefly habitat
The biggest threat facing fireflies today is the loss of their habitats. But with about 2,000 different species of fireflies, there’s a wide variety of environments in which they thrive—including wetlands, forests, and even city parks—which is why some species are more threatened than others.
In any habitat, however, Lewis says to start by thinking about their lifecycle. Although people most commonly see fireflies as adults, these insects undergo four stages of metamorphosis: eggs, larvae, pupae, and adults. Throughout most of these stages, fireflies live underground or in moist soil where they can prey on earthworms, their favorite food.
You can recreate those conditions in your own backyard simply by leaving some woody debris and leaf litter around the edges of your property.
“That’s a good microhabitat for baby fireflies,” Lewis says.
You could also plant native shrubs and trees and let your grass grow long—all of which will help soil retain the moisture that fireflies love.
Turn off your lights
The same glow that makes fireflies so remarkable also makes them especially vulnerable to the rise in light pollution.
Flashing lights are an important part of the firefly mating ritual. As the sun fades each night, male fireflies flutter around while flashing their lights to signal their interest. If a nearby female is interested, she flashes back from her perch on the ground, and the males fly down to find her.
“All of that has to happen for the next generation to survive,” says Becky Nichols, an entomologist at the Great Smoky Mountains National Park, home to a particularly dazzling species called synchronous fireflies.
City and suburban lights make those cues much harder to see. One recent study showed that excess light at night—no matter how dim—reduces the amount of flashing among males, as well as the female response rate.
“It's like cutting a phone line,” Lewis says. “It really quashes the romance.”
Fortunately, there are some solutions. You can install motion sensors, timers, or dimmers on any lights outside your home, draw your curtains shut at night to prevent light from seeping out the window—and turn off the lights completely when possible. Shielded coverings for street lamps and outdoor lights also help. (For more tips, check out the Xerces Society’s firefly-friendly lighting guide.)
What about colored lights? Although red light has long been considered okay for fireflies, Lewis says that thinking is changing. Whenever possible, darkness is the answer.
Stop using pesticides
Spraying your yard with pesticides and insecticides also poses an existential threat to fireflies—which are insects after all.
Lewis points out that most of the pesticides marketed to home gardeners are broad-spectrum chemicals that will kill firefly larvae just as swiftly as they kill ants, wasps, and other less-beloved insects.
Scientists are researching alternatives to chemical pesticides that could target specific species, like mosquitoes, while leaving other insects unharmed.
Practice good firefly tourism
Fireflies are so enchanting that they’re now the main attraction at tourist sites across the world—from the Great Smoky Mountains in the U.S. to Nanacamilpa in Mexico and the Daan Forest Park in Taiwan. Research has shown this can be a double-edged sword, encouraging an appreciation for fireflies while also disrupting their life cycles and habitats.
When visiting firefly habitats, watch where you’re walking to avoid trampling on mating adults—or their developing larvae. If a firefly-watching destination has installed raised walkways to protect fireflies, don’t stray from it.
These destinations may also allow you to bring a flashlight to help you find your way to the perfect firefly viewing spot. If you do, make sure to cover it with a dark red filter—but Lewis points out that it’s better to arrive early when it’s still light out so you don’t need a flashlight at all.
Get involved in firefly conservation
There are a number of other ways you can help fireflies beyond your backyard—from supporting a national conservation organization like Xerces Society to working with your community to establish a firefly sanctuary. (For inspiration, Lewis points to a firefly sanctuary and walking trail built on 6.5 acres of land in New Canaan, Connecticut.)
If you live in a North American region that’s home to threatened firefly species, you can also contribute to a citizen science project. In late March, the Xerces Society and IUCN Firefly Specialist Group launched the Firefly Atlas to track and learn more about the lives of the 13 most endangered species.
Lewis says the IUCN group is working to assess the conservation status of fireflies in other parts of the world beyond the U.S. and Canada. But, she adds that we already know enough about the environmental threats facing the most at-risk species, and protecting fireflies from these threats can benefit the entire ecosystem they depend on.
“Every one of those species has a particular niche that it fits into,” she says. “Here is an amazing portal to the miraculous that’s worth protecting.”