Fireflies are some of our most beloved insects, creating fond memories of summer evenings for generations. But in recent years, people have noticed they aren’t seeing as many fireflies.
Chris Hartley, Manager of Living Collections, Education, and Facilities at the Sophia M. Sachs Butterfly House, says there are a few reasons for this.
“It seems every generation tends to remember more of certain charismatic species such as butterflies or fireflies being around when they were kids compared to when they were adults,” Hartley said. “This is likely in part due to children spending more time outside as children, and this is a phenomenon that has existed for generations.”
“However, there is also data showing that groups of many insects, including fireflies, are absolutely less common than they a few decades ago.”
Fireflies: Childhood Companions, Pollinators
Fireflies are wonderful ambassadors of the insect world.
Generations of children have cherished memories of chasing, catching, and releasing fireflies during warm summer evenings. They are some of the first insects young people will explore in their natural environments.
Along with being excellent ambassadors, fireflies are also pollinators.
Many adult fireflies are generalist pollen feeders as adults, meaning they can pollinate a wide variety of plants. Because of this, fireflies are especially important in areas where traditional pollinators like bees may be in decline.
Fireflies also eat snails and slugs as larvae, which helps to keep ecosystems in balance.
These important insects play vital roles in the natural world, which is why their decline is alarming for scientists.
The Disappearing firefly
Scientists have noted a decline in fireflies species around the globe.
A paper published in 2021 analyzed 132 of the 169 firefly species found in the United States and Canada. Of those 132, nearly a third were found to be threatened by extinction.
In 2024, the U.S. Fish and Wildlife Services (USFWS) proposed the Bethany Beach firefly (Photuris bethaniensis), which is native to Maryland and Delaware, be listed under the Endangered Species Act (ESA) as “Threatened’. This is the same designation proposed for Monarchs the same year. The Bethany Beach firefly was the first firefly species proposed to be listed under the ESA.
On a global scale, many scientists look for guidance from the IUCN, an international non-governmental scientific organization that recommends species for conservation protection.
The IUCN currently lists about 80 firefly species in their database, with approximately 40% of those species being imperiled to some degree. Many species are listed as endangered or critically endangered
Disrupting the firefly lifecyle Is leading to population decline
Understanding the firefly lifecycle can help us understand why they are declining.
Fireflies have a complete metamorphosis with a larva that can spend 1 to 3 years on the ground before becoming an adult firefly.
“They need their habitat to be undisturbed and free of danger for the whole time they are in the larva stage,” Hartley says. “Once they become adults, they have just a few weeks to find a mate and lay eggs to begin the next generation.”
Insecticide use, habitat destruction, light pollution, and climate change all disrupt this lifecycle.
Insecticide, Pesticide, and Herbicide Use
We know fireflies fly at night, but for the rest of the day they sleep on vegetation. In your yard, they may sleep in a flower bed, lawn, areas covered by leaves, or any similar area.
It is important to eliminate or reduce the amount of chemicals to protect all these areas that fireflies need.
Additionally, firefly larvae are predators of snails, slugs, worms, and other invertebrates. Pesticides can affect these animals and remove the food source for firefly larvae.
Herbicides can also have an affect on fireflies by removing the plant diversity that they depend on for daytime shelter.
How to help: Limit or eliminate the use of insecticides, pesticides, and herbicides in your yard and garden. You can learn more about organic gardening at the Kemper Center for Home Gardening.
Firefly Habitat destruction
Fireflies thrive in moist areas with lots of vegetation such as near rivers, around lakes and ponds, and moist fields along forest edges. Unfortunately for fireflies, these areas are targeted by developers for either residential or commercial purposes.
Human activity also changes waterways through dams and the channeling of streams. Many times, wetland areas are targeted for removal because they are seen as undesirable for residential and commercial areas.
On a smaller scale, in residential areas the removal of leaf litter has contributed to firefly decline. Most species of fireflies overwinter as larvae, burrowing underground or under leaf litter.
Commonly accepted practices such as raking leaves each fall are magnified as the number of homes in a particular area increases.
How to help: Leave the leaves in fall. Leaf litter is a vital for many overwintering bugs, including fireflies. Learn more about leaving the leaves in autumn.
Climate change
Garden research has found that climate change is speeding up the bloom times of Missouri flowers. Hartley says that some adult fireflies will take pollen or nectar from these flowers impacted by the advanced bloom time.
The bigger, more concerning impact of climate change on firefly populations comes from longer warm periods and drier conditions. These longer periods of warmer weather tend to dry out the damp ground and leaf litter that fireflies need to survive.
How to help: Welcome fireflies into your yard by adding shrubs, grasses, or other taller vegetation. Frequent mowing of your lawn can disturb adult lightning bugs so try reducing your mowing or create a mow-free zone in your yard.
Light pollution and mating impact.
Firefly adults only live for a few weeks, and during that time they are entirely focused on finding a mate. They find each other through the flashes we see in the summer evenings.
Firefly flashes are pretty dim compared to the artificial lights in our cities, which include porch lights, streetlights, car headlights, and many other sources. These light sources can interfere with fireflies finding each other to mate.
How to help: Decrease light pollution by carefully choosing the lights around your home. you can also use motion-detecting lights that are only on when needed.
Help keep fireflies around for another generation
We’ve outlined several ways you can help fireflies near your home and communities, but kids can also get involved. In fact, we want them to!
We know that when young people connect to nature, including fireflies in their backyard, they are more likely to be good stewards of nature in the future.
When it comes to catching fireflies, the best approach is to gently catch them in a clear, clean jar and release them that night. If you leave lightning bugs in a jar overnight, 90 percent of the time they will die, even with air holes.
Children can also learn about fireflies through Project Pollinator, a community-oriented program from the Butterfly House that promotes an appreciation of all pollinators through education and creation of pollinator gardens.
Fireflies and Friends Festival
Celebrate the bugs of summer at the Fireflies & Friends Festival! Great for all ages, the evening will be filled with live music, fun activities, and hands-on exploration as you learn about dragonflies, cicadas, fireflies, and more on June 27.
Jessika Eidson | Public Information Officer
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Chris Hartley | Manager of Living Collections, Education, and Facilities at the Butterfly House
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