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Conservation Corner

Lighting Bugs, Glowing Insects with a Dark Side

By Dan Zarlenga, Missouri Department of Conservation

There’s something magical about seeing a mass of fireflies pulsing in a field. It’s almost as if a cluster of stars descended twinkling from the sky. Fireflies are a real treat starting as early as May. But did you know fireflies aren’t really flies? And they’re light produces no fire? And in fact, some of these lightning bugs even have a darker side.

The nighttime insects we commonly call fireflies or lightning bugs are actually beetles. There are many different species that inhabit our state, though they all look very similar to our eyes. Of course, what catches our attention are the magical flashes they create. The last few segments of their abdomens are pale yellow and can glow in distinct colors, mainly yellow or green.

Fireflies use a trick called bioluminescence to create their amazing light. The glow comes from chemical reactions much like what we see in glowsticks. An enzyme in lightning bug bodies called luciferase makes the light yet produces almost no heat in the process. Scientists would love to build a lightbulb that efficient! Fireflies are Missouri’s only flying, bioluminescent insects.

What do the flashes mean? Scientists believe they are a Morse code of courtship and are used so male and female lightening bugs can communicate and find each other. In addition to variations in glow color, each species has its own special language and flash patterns. Only the fireflies themselves know what they mean.

Fireflies are common in this area, although more so in less developed ones. We can see them in local parks, meadows, edges of forests, and around streams, and even in backyards. They begin emerging in late spring and can be seen through summer. Their adult lives, the stage when they can fly, is only about two months.

In an earlier stage of life, when they are larvae, fireflies are known as glow worms. In this phase they neither fly nor flash. Glow worms are wingless and stay on the ground, especially in moist and brushy areas, where they’re seen as small, eerie orbs of steady light. These larvae are voracious predators and their jaws have toxins that overpower snails, slugs, earthworms, and other prey for food.

Beautiful and luminescent as they are, some fireflies use their light for a dark purpose. After they successfully mate, females of certain species change into man-eaters. Now their charming flashes attract meals instead of mates. Still others mimic the courtship signals of another species to lure in unsuspecting “mates,” to eat. Unfortunate is the firefly who comes looking for love and ends up becoming lunch! At least fireflies don’t have to worry about getting eaten by much else because their bodies contain chemicals that make them very distasteful to other predators.

Even though fireflies are not flies and have no fire, that doesn’t take away from their beauty and the awe they inspire. With a little more enlightened on lightening bugs, why not venture out on a warm night and see if you can decode their secret messages.

For information visit www.MDC.mo.gov.

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