Illuminating Lightning Bug Facts You Didn’t Know

Get answers to common lightning bug questions. Find out why lightning bugs light up, when lightning bugs come out and more.

Facts About Lightning Bugs

Lightning bugs in a forestsnjewelry/Getty Images
Lightning bugs light up a forest

Whether you are lucky enough to see a lightning bug in your backyard or plan to head to a local spot for prime viewing, lightning bugs (aka fireflies) are synonymous with summer. Let’s illuminate some little-known truths about these fascinating, glowing creatures.

Firefly vs Lightning Bug

More than 2,000 species of lightning bugs and fireflies exist worldwide, including 170 in North America. But what’s the correct name? According to Adele Wellman, Allegany region environmental educator for New York State Parks, calling them either fireflies or lightning bugs is fine. “There is no difference between them; they are the same insects,” she says.

Though both names are correct, these flashers are technically neither bugs nor flies. Instead, they are beetles. Next time you’ve got one in your hands, look closely for hardened wing cases, the elytra. This is a key beetle characteristic.

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How Long Do Lightning Bugs Live?

A lightning bug perched on a blade of grass, its abdomen lit in bright yellow light.James Jordan Photography/Getty Images
A lightning bug perched on a blade of grass, its abdomen lit in bright yellow light

“Fireflies go through complete metamorphosis,” Adele says. “They lay eggs in moist areas, and these hatch in about two weeks. The larvae grow for months, pupate underground or beneath tree bark, and then transform into adults.”

Adulthood is short-lived for these beetles. Most adult fireflies survive for just days or weeks.

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What Do Lightning Bugs Eat?

Lightning bug larvae are voracious. Adele says that the small, armored, leggy predators live on earthworms, slugs and snails.

Though some adults do not eat at all, the predatory females in the Photuris genus mimic the flashing patterns of other firefly species to lure and eat males.

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How and Why Do Lightning Bugs Light Up?

A lightning bug lands in the center of a pink cosmos flower and lights it with a soft glow as its petals begin to furl for the evening.Courtesy Brittany Kershner

Not all fireflies flash, but both the eggs and larvae glow. Scientists think this is a hint to leave young fireflies alone—a clear warning to would-be attackers of their potentially bitter taste. Adult firefly abdomens have light-producing organs. Within these lanterns, chemicals, enzymes and other compounds mix to produce light.

The blinking rates can help identify different species. “It may take a while for your eyes to adjust, but when they do, note how many different flash patterns you see,” Adele says.

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Some Lightning Bugs Flash in Unison

One fascinating type of firefly flashes in unison. In the U.S., these synchronous fireflies were once thought to live only in the Smoky Mountains, but recently they’ve been discovered in other pockets along the Appalachians.  Synchronous fireflies prefer mature, dark forests, according to Adele. One of her favorite programs at Allegany State Park is leading firefly trips that include viewing synchronous species.

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When Do Lightning Bugs Come Out?

Lightning bugs flicker while hovering over a cornfield in Amity Township on Tuesday, June 19, 2018. IMAGE Weather Art Enterprise Wild Art RNP Really Neat Photo Last Look Spadea. Photo by Jeremy DreyMediaNews Group/Reading Eagle via Getty Images/Getty Images
Lightning bugs flicker while hovering over a cornfield 

With so many species worldwide, lightning bugs are found in many habitats, including deep woods, meadows, marshes, swamps and fields. They often like to be near water sources.

“They prefer hot and humid nights,” Adele says. “Heavy rains or cooler temperatures cause them to slow their flash.”

Light hampers fireflies’ ability to see one another, so these bright beetles seek out dark areas. The summer viewing season begins as early as May and lasts until September—peak watching coincides with the warmest months of the year.

If you want to help researchers monitor these bright fliers, record your sightings with the Firefly Watch program.

How to Watch Lightning Bugs

Follow environmental educator Adele Wellman’s top hints for observing nature’s fireworks:

  • Wear long pants and sleeves. If you must use bug spray to repel biting insects, do not handle fireflies.
  • Use a red- or blue-light flashlight to avoid confusing them.
  • Walk carefully, as many female fireflies land on the ground.
  • Bring a chair or a mat so you can sit back and enjoy the flashing glow.

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Ken Keffer
Professional naturalist and award-winning environmental educator and author Ken Keffer has penned seven books connecting kids and the outdoors. Ken is currently on the Outdoor Writers Association of America Board of Directors. Ken was born and raised in Wyoming. He's done a little bit of everything, from monitoring small mammals in Grand Teton National Park to researching flying squirrels in southeast Alaska. Ken enjoys birding, floating on lazy rivers, fly fishing, and walking his dog.