Fireflies Are a Summer Delight

A Blog Story About Nature in Our DuPage Forest Preserves

Fireflies are a Summer Delight

Posted by Forest Preserve District of DuPage County | 7/16/18 11:09 AM

The twilight twinkles of fireflies, or lightning bugs, is one of the sure signs of summer. Most of us have fond memories of spending warm summer nights chasing them. Fireflies are fascinating creatures, but they’re not really flies – they’re beetles. The Lampyridae are a family of insects in the beetle order Coleoptera. They are winged beetles, commonly called fireflies or lightning bugs for their conspicuous use of bioluminescence during twilight to attract mates.

There are many species of fireflies. In the United States, there are about 136 species, while DuPage County has only three. Each species has its own pattern of flashes to set it apart from other species. Usually it’s the male that you see flying around open areas of your yard. The female is usually perched on the ground or on a bush. If she likes what she sees, she will respond with another set of flashes.

There's this back and forth that you see but there's kind of a code to it, so each species knows who each other are.

It’s OK to catch them and put them in a jar, but keep the jar moist with a damp paper towel, and don’t keep them for a long time because they’ve got work to do.


The Great Smoky Mountains is one of the few places that has a synchronous species of fireflies that all flash at once. Their mating display usually takes place during a two-week period between May and June, according to (Photo courtesy of  

Some interesting facts about fireflies:

  • Fireflies west of the Rocky Mountains do not flash.

  • Photinus carolinus are the only species in America that flash simultaneously’ one great place to see them is the Great Smoky Mountains National Park. *

  • A chemical called luciferin inside their abdomen/tail combines with oxygen, calcium and adenosine triphosphate, a chemical reaction occurs to create their spectacular light. *

  • The light produced by the firefly is the most efficient light ever made. Almost 100 percent of the energy in the chemical reaction is emitted as light; in comparison, an incandescent light bulb only emits 10 percent of its energy as light, the other 90 percent is lost as heat. *

  • Fireflies taste disgusting: Predators looking for a light meal quickly discover fireflies taste very bad. Firefly blood contains lucibufagins, a defensive steroid that tastes really gross. Predators associate the bad taste with a firefly’s light and learn not to eat bugs that glow. *

  • Fireflies light up the underworld. Or underground, at least. While it’s true that many an insect larvae lives underground, some firefly babies emit a subterranean glow. Among some species, even the eggs glow.

  • Firefly populations are declining, possibly due to habitat loss, light pollution and insecticides. 

BLW (16) 72dpi

* Source: Mother Nature News

Topics: Insider, Take 5, Wildlife, Nature

Written by Forest Preserve District of DuPage County

The Forest Preserve District of DuPage County welcomes more than 6.2 million visitors a year; and manages nearly 26,000 acres in 60 forest preserves containing prairies, woodlands and wetlands.