Lakeside Nature Center

Critter Corner - Firefly


Fireflies are really beetles.  Fireflies produce light through a process called bioluminescence.  A combination of oxygen and chemicals results in the release of carbon dioxide and visible light, with virtually no heat!  Eggs and larvae of some firefly species also glow.  There are dozens of firefly species found in the United States east of the Rocky Mountains, and more than 1,000 around the world.


As adults, some firefly species do not eat at all.  But the larvae are all predators, feeding on bugs, snails, slugs and earthworms by injecting digestive enzymes into the victim and sucking out the liquefied parts.


A female firefly may lay 100 or more glowing eggs in soil.  Larvae hatch from the eggs in three to four weeks.  The larvae eat all summer and dig down into the soil during winter.  They emerge again in the following spring to continue eating and growing.  After another year, the larva forms a cocoon and pupates for about 10 days and then emerges as a full-grown adult.  The adult may live only a couple of weeks.


Many firefly species choose meadows, lawns and fields.  Some prefer shrubs and trees.  Edges of woods and streams are often active firefly habitats.  Different species are active at different times of the evening and into the night.


Fireflies have few defenses and are preyed upon by those animals that eat insects.  If you catch fireflies on a warm summer evening, observe hem for only a few minutes and let them go again.


  • Male fireflies fly around and signal with their lights.  The females signal back while perched on a blade of grass or twig.  Through a series of signal and responses, the male is able to find the female of its own species.

  • each species has its own code, or flash pattern, and different shade of green, gold or pale yellow.

  • The warmer the temperature outdoors, the better their lights work.

 (Photo credits:  Large firefly from European Physical Society web page; firefly on leaf from Ohio State Educational website)


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