How to Be a Friend to Fireflies

Lightning bug populations are in trouble, but there are some simple things we can do to help.

I have fond childhood memories of summer evenings dancing in tall grass, gently scooping lightning bugs into my cupped hands. The overgrown hedgerows of my grandparents’ yard hosted sparkling displays of syncopated light, transforming a mundane backyard into a fairy realm.

I had mostly forgotten the breathtaking bioluminescent beetle displays I enjoyed as a child, the gentle yellow flashes of light buried in the recesses of memory. There aren’t many fireflies these days. I only occasionally catch sight of their mellow flickering while cruising dark country backroads after sunset. They aren’t the constant and reliable summertime presence for me in adulthood that they were in my salad days.

There has been a noticeable and somewhat alarming decline in firefly populations globally. Not only have our yards become boringly twinkle-free, but declining lightning bug numbers could signal broader ecological issues that could lead to the total loss of an important natural phenomenon.

Photo by Tony Phan on Unsplash

Habitat loss is one of the most significant factors contributing to the firefly decline. Fireflies thrive in specific environments with conditions supporting all life cycle stages. These habitats include wetlands, forests, grasslands, and areas near bodies of water. Rapid urbanization and industrialization have destroyed and fragmented these natural habitats.

Urban and suburban sprawl is another serious threat to my lightning bug friends. Human presence continues to slowly encroach upon natural landscapes, replacing verdant forests and fields with buildings, roads, sidewalks, and manicured yards, all of which are less-than-stellar environments for fireflies. Fragmented habitats make it difficult for fireflies to find mates and maintain healthy populations. Patches of suitable habitat become isolated, reducing genetic diversity and increasing the risk of local extinctions.

The Light Pollution Problem

Light pollution is another critical factor affecting firefly populations. Fireflies don’t have Tinder, so they have to rely on bioluminescent signals to find their mates. Fireflies glow to attract a mate. Males use distinct light patterns to let females know where they are. It’s like sending a late-night hit-me-up booty call text. The females, who typically remain perched on tall grasses, signal back if they’re interested.

Photo by Jarrod Reed on Unsplash

Artificial light from streetlights, buildings, and vehicles interferes with these signals, making it difficult for fireflies to locate each other and reproduce. Studies have shown that firefly populations are significantly lower in areas with high levels of light pollution than in darker places.

In addition to disrupting mating signals, light pollution can alter lightning bug behavior. Excessive artificial light can turn fireflies into lazy sluggards, reducing their feeding and mating activities. This behavioral change can lead to lower reproductive success and declining population numbers.

The Perils of Pesticide

Another major threat to fireflies is the widespread use of pesticides. Agricultural and residential insecticides can devastate non-target species like fireflies.

Fireflies, in particular, are highly susceptible to insecticides. These chemicals kill them at various life cycle stages, from larvae to adults. Larvae, which live in the soil or leaf litter and are exposed to soil-applied pesticides, are particularly vulnerable. Adult fireflies also face high mortality rates when exposed to insecticides through contact with treated surfaces or ingesting contaminated prey.

Pesticides can also indirectly affect firefly populations by reducing the availability of prey. Firefly larvae feed on small invertebrates, many of which are also affected by pesticides. A decrease in prey availability leads to lower larvae survival rates, ultimately reducing adult firefly populations.

Apolitical Climate Change

While climate change can be an extremely polarizing political topic, it is difficult to argue against the fact that our planet is experiencing serious changes in temperature and precipitation patterns. Even if the jury is (mostly) still out on whether or not people are directly to blame, climate change poses a complex and multifaceted threat to fireflies.

Fireflies are ectothermic, meaning their body temperature and metabolic rates are influenced by external temperatures. Wild temperature variations can alter the timing of firefly emergence and mating periods. Warmer temperatures can lead to earlier or prolonged seasons, disrupting the synchronization of mating signals. This temporal mismatch can reduce reproductive success.

Many firefly species depend on moist environments for their survival. Changes in precipitation patterns, including increased frequency and intensity of droughts or flooding, can alter the availability of suitable habitats. Drought conditions can dry out wetlands and other moist habitats, while excessive rainfall can lead to habitat flooding, both of which are detrimental to firefly populations.

Looking After Lightning Bugs

Although declining firefly numbers are concerning, all is not lost. Despite the challenges, several measures can help conserve firefly populations and mitigate factors contributing to their decline.

While reversing climate change and saving our dwindling wetlands is a tall order for individuals, we can do several easy things to help our firefly friends right in our own backyards.

1. Let your yard go wild. While your HOA and overly Karen-y neighbors may frown upon it, high grass and shrubbery are a lightning bug’s favorite places. The National Gardening Association recommends letting the perimeter of your yard grow wild to create these favorable conditions. At the very least, mow less often to prevent murdering unsuspecting fireflies as they rest on tall blades of grass during the daytime.
   

2. Turn off the porch light. Fireflies glow to attract a mate. Males use distinct light patterns to let females know where they are. It’s like sending a late-night hit-me-up booty call text. The females, who typically remain perched on tall grasses, signal back if they’re interested. Since bright outdoor lights can outshine lightning bug butts, interfering with mating behavior, you can lend fireflies a hand by flipping off the switch after the sun goes down.
   

3. Plant native trees. Planting native trees, particularly native pine trees, helps fireflies in several ways: Thick canopies help block artificial light that could interfere with mating, and the needles that drop to the ground create an ideal nursery for young larvae.
   

4. Skip the Poison. Replace chemical pesticides with more natural insect control methods in your yard and garden. Attracting fireflies to your yard can also act as natural pest control, as the larvae like to feast on snails and slugs.
   

5. Add a backyard water feature. Fireflies love moisture. Most live and mate where forests and fields meet streams, but they also congregate around small puddles and other standing water during the mating season. If you're not concerned about mosquitoes (who also love to party in damp places), consider adding a small pond in your backyard to give them a new favorite hang-out spot.