If you’ve stepped outside on a warm summer night in Illinois this year, you may have noticed something magical: fireflies, and lots of them. Swarms of these iconic insects have lit up parks, backyards, and natural areas across the state, offering a rare glimpse of hope after decades of population decline.
But while this summer’s glow has thrilled nature lovers, it’s not yet time to celebrate a full comeback. Firefly populations have been steadily shrinking due to habitat loss, widespread pesticide use, and light pollution. The good news? There are simple, science-backed steps we can all take to help these glowing insects thrive again.
Why Fireflies Are Disappearing
Fireflies (also known as lightning bugs) aren’t just summertime entertainment—they’re an important part of the ecosystem. But over the years, Illinois has seen a steep decline in firefly populations. The primary culprits?
- Loss of habitat: Development, monoculture lawns, and aggressive landscaping have replaced the moist, organic-rich habitats fireflies need to breed and feed.
- Pesticides: Many common lawn and garden chemicals harm fireflies directly or kill off their food sources, like slugs and snails.
- Light pollution: Artificial lights interfere with the flashing signals fireflies use to find mates.
Native Plants and Grasses: A Firefly-Friendly Foundation
One of the most effective ways to support fireflies is by restoring the habitat they’ve lost—and that starts with planting native species.
Native wildflowers, shrubs, and especially native grasses are crucial to the firefly life cycle. Firefly larvae spend most of their lives in the soil, where they hunt small invertebrates. These larvae are extremely sensitive to moisture levels. Too wet, and they drown. Too dry, and they desiccate.
That’s where native grasses shine. Species like big bluestem, little bluestem, and switchgrass act like natural sponges. Their deep, fibrous roots help retain moisture when it’s scarce and drain excess water during heavy rains—creating a “just right” Goldilocks zone where firefly larvae can survive and thrive.
Whether you’re working with a small backyard or managing a larger-scale restoration project, planting native vegetation is one of the most powerful steps you can take to bring fireflies back.
Skip the Sprays: Pesticides to Avoid
Even the most firefly-friendly yard can become a danger zone with the wrong products.
Many common grub and lawn insect control treatments contain neonicotinoids—systemic insecticides that persist in soil and are lethal to non-target insects like fireflies. Other ingredients to watch out for include:
- Imidacloprid
- Clothianidin
- Carbaryl
- Diazinon
- Pyrethroids
These chemicals kill not only adult fireflies and their prey, but also contaminate the leaf litter and soil where larvae live. Mosquito foggers and broad-spectrum sprays can be just as damaging, eliminating entire webs of insect life.
Instead, consider a pesticide-free approach to lawn care. Let leaf litter accumulate in areas of your yard. Allow some space to grow a little wild. Create pockets of refuge where nature can do its work uninterrupted.
Fireflies Need Both Small Yards and Big Landscapes
Restoring firefly populations isn’t just about individual backyards—it’s also about large-scale action. When native plants and thoughtful stewardship are implemented across prairies, park districts, and preserves, we give fireflies the connected habitat they need to move, breed, and survive long-term.
From homeowners to conservation professionals, we all have a role to play.
Let’s Keep Illinois Glowing
The resurgence of fireflies this summer is a hopeful sign—but it’s not a guarantee. With continued habitat restoration, native planting, and a shift away from harmful chemicals, we can support a long-term recovery for these beloved beetles.
Want to help? Start by planting native. Choose native grasses and wildflowers adapted to your region. Avoid pesticides that disrupt soil life. And let your yard go a little wild—you just might be rewarded with a front-row seat to nature’s light show.