Nature Nearby: Fireflies (AKA Lightning Bugs) Provide Summer's Real Fireworks

Nature Nearby: Fireflies (AKA Lightning Bugs) Provide Summer’s Real Fireworks

  • Nature Nearby is written and photographed by Valerie Blaine, the nature programs manager for the Forest Preserve District of Kane County. You may reach her at

The Fourth of July brings spectacular light shows with bedazzling explosions of color in the night sky. Thousands of dollars are spent on these extravaganzas. But there’s another light show going on, independent of Independence Day, and this one is just as awesome: fireflies! Their light show is performed nightly, for free, throughout July.

Fireflies, or lightning bugs, are among the few insects that are universally loved by people. They inspire “oooh’s!” and “ahhh’s!” from young and old alike. What, exactly, are these creatures?

The good, old Mason jar technique of observing fireflies! If handled gently, fireflies can be put in jars to admire. Be sure to release them so that they can make more fireflies for next year. (Photo courtesy of Valerie Blaine)

The lovely little blinking insects are neither bugs nor flies. They’re beetles, and fab ones at that. They belong to  the family Lampyridae, which is Greek for “shining ones.” Worldwide, there are more than 2,000 fireflies. Here in Kane County, there are about a half a dozen species (depending on which entomologist you talk to!).

Fireflies’ claim to fame is, of course, the fact that they can light up. A creature that can produce its own light is bioluminescent. (Note: there is a wide variety bioluminescent organisms, including fungi, fish and octopuses.)

The light produced by fireflies and other bioluminescent creatures is way cool. Seriously. A firefly’s light is 90 per cent efficient and barely loses any energy as heat. This far surpasses our most energy-efficient household appliances. Modern light technology with all the new kinds of LED bulbs, has not yet achieved the energy efficiency of a firefly.

The question of how bioluminescence works has been piqued the curiosity of laymen and scientists for years. Here’s the scoop: Light is produced at the end of the firefly’s body in a photic, or light-producing, organ. (Some entomologists simply call it a lantern.) You can observe this if you hold a firefly gently and wait for it to blink.

See those segments at the end of the insect’s abdomen? This is the “happening” part of the firefly, where a pigment called luciferin, an enzyme known as luciferase, a chemical compound called ATP, and oxygen react together. “Let there be light!” the firefly says.  And, there is.

Why do fireflies create this light? They do it for love. The males blink to woo demure females who are watching from the a perch near the ground. As the males flash from above, the females must discern who’s signaling. They can detect the species-specific pattern and color of flashes.

This female firefly, perched on a leaf near the ground, is signaling to a male flashing in flight above her. (Photo courtesy of Valerie Blaine.)

If a female sees the right guy, she flashes a come-hither signal back to him. If all goes well, they mate. The female then produces eggs and buries them in the ground. The eggs will mature into larvae (sometimes called glow worms), then metamorphose into pupae.

Many months later, they become adults. This is the new generation of fireflies who will put on next summer’s light show, enchanting a new generation of kids running in the grass to catch them.

As much as we love fireflies, these insects are negatively impacted by our suburban lifestyles. The three main culprits are habitat loss, pesticides, and light.

Suburban “lawnscaping” does not make good firefly habitat, particularly with heavy pesticide use. Lawns may seem great to us, but they are degraded habitat from the viewpoint of a firefly. Flower and vegetable gardens are better habitat, as long as pesticide use is kept at a minimum. Overall, the best landscaping for firefly populations is a diverse array of native plants. (More on that in another column!)

People don’t give much thought to light pollution — in fact, many people aren’t even aware that there is such a thing! But artificial light is anathema to nocturnal critters. Porch lights, parking lot lights, and security lights all contribute to fireflies’ woes. Because fireflies communicate in a language of light, they have to have darkness to “talk” to each other. Their flashing is an entomological Morse code to attract mates, defend territory and send warning signals to potential predators. The more ambient light at night, the more difficult it is for fireflies to read each other’s signals.

There’s an easy fix to light pollution. It’s 100 percent effective, and it will save you money. Turn the lights off! If you’re not comfortable with turning all the lights out, you may want to re-evaluate your lighting needs. If you feel you need outside lighting, direct the light where it will be most effective. Often, that is the immediate perimeter of your house, not out into your lawn (or the neighbor’s bedroom window!).

Fireflies are wonderful insects that have delighted generation after generation of children. The sight of thousands of blinking lights in the woods also tugs at the heartstrings of adults, bringing fond memories of summers past. Whether their light shows fill you with nostalgia or inspires you to restore habitat for future generations, take time this month to enjoy them.

If you’d like to learn more about fireflies, check out the Forest Preserve District of Kane County’s “Firefly Fireworks” program at Campton Forest Preserve from 8:30 p.m. to 9:30 p.m. Saturday, July 8. Forest Preserve District naturalists will lead a walk and talk at dusk, explaining the how’s and why’s of lightning bug lights. We’ll carefully catch some to observe their lanterns, and then release them back into the field.

Advance registration is required. Call 630-444-3190 or email

Sign Up Now For Firefly Fireworks July 8 at Campton Forest Preserve