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Lightning Bugs on the Decline

Written by Rhonda Ferree, retired horticulture educator

I hear a news report about the decline of the monarch butterfly almost every day, but there are other insects in decline as well. One that is a favorite of all ages is the lightning bug, which some folks also call a firefly.

As a kid I remember catching lightning bugs on warm, summer nights. We put them in empty canning jars or pickle jars, poked holes in the lids, and watched the bugs glow in our new natural lantern. Although I hate to admit it, I also sometimes ripped off the abdomen of the bug to make a glowing ring on my finger.

Lightning bugs flash light to attract the opposite sex using a chemical called luciferase. There are over 136 species of lightning bugs, each with a distinctive rate of flashes per second. Male lightning bugs flash patterns of light to females who then signal in response from perches in or near the ground. When the male sees the female's flash he continues to signal and moves closer until they finally find each other and mate.

Lightning bugs are actually a type of beetle that is very beneficial in our ecosystem. The larvae stage of this beetle is a specialized predator that feeds on other insect larvae, earthworms, snails, and slugs. The tiny larval stage is dark gray with three pairs of legs and tiny spots on their underside that sometimes softly glow. Some adult lightning bug species are also predators, and other species don't eat at all in the adult stage.

Large swarms of lightning bugs are a less frequent occurrence in many areas. I can remember a midnight float down the Illinois River a few years ago when the river bank was alive with millions of flashing fireflies. This summer I saw lightning bugs, but not in large numbers. They are most prevalent away from city lights and in more open areas of vegetation.

According to firefly populations are dwindling all over the country, and the world. Researchers are not sure exactly what is causing the firefly decline, although most researchers think that habitat loss and light pollution from urban development are to blame.

Most fireflies need undisturbed natural areas to survive. They overwinter as larvae buried in the soil and hide during the day under bark or stones or in decaying vegetation. Mud is needed for the pupal stage. Human light pollution is believed to interrupt firefly flash patterns and thus their mating rituals.

If you want to help researchers learn more about this insect, consider participating in a fun citizen scientist project called Firefly Watch. You simply watch fireflies in your own backyard or favorite outdoor location and record those observations online at

The next time you see one of these magical insects, think about how they are more than just funny flashers. They benefit our ecosystem and are also beneficial to humans. Their luciferase has been genetically engineered as an enzyme that helps screen for human tumors, test for blood problems, and detect infections faster. Wow!



As horticulture educator, Rhonda Ferree inspired citizens in local communities to grow their own food and improve their home landscapes. She focused on high quality, impactful programs that taught homeowners how to create energy-efficient landscapes using sustainable practices that increase property values and help the environment.

After 30 years with University of Illinois Extension, Rhonda retired in 2018. She continues to share her passion for horticulture related topics as “Retro Rhonda” on social media.

ILRiverHort is a blog that helps people connect to nature and grow.