Wilderness Underfoot: Lightning bugs

StoryImage( ‘/Images/Story//Auto-img-11515210497216.jpg’, ”, ‘The lightning bug – With 125 species in the U.S., and 2,000 worldwide, this is a diverse member of the order of beetles.’);

Nearly every adult can remember the childhood magic of catching these mysterious glowing beetles

The twinkling of the lightning bug is an alluring sight for any child as the hot summer day comes to a close, and the cool of night moves in. Also known as a “firefly,” this animal’s trick of switching its internal light on and off has fascinated humans since long before we mastered fire or electricity.

When organisms such as the lightning bug manufacture their own light, we call this feat “bioluminescence.” In lightning bugs, the glow is created within their lower abdomens when the enzyme luciferase comes into contact with the compound luciferin. Throw in a dash of oxygen, and out comes light.

Although other kinds of insects are capable of glowing, only lightning bugs have been found to use specific flashing patterns to signal each other. Like other animals that rely on extravagant displays, lightning bugs use their flamboyant flashing as part of a mating ritual. Typically, lightning bugs within a single species will use distinct lighting patterns to attract one another. They may also add certain flight patterns—for example, members of one species form a glowing shape like the letter “J.”

In the ritual, the male flashes, the female responds with the appropriate flash pattern, and the male moves in until he finds her. Females are flightless, and typically they don’t initiate the signals.

Entomologists studying fireflies can differentiate various species by watching the number of flashes, their duration and the intervals between flashes.

With their own take on the expression, “Liar, liar, pants on fire!” the females of the Photuris genus of lightning bugs will mimic the blinking of males belonging to other species. When males arrive with libidinous intentions, the poor fellows are cruelly pounced upon and eaten! This murderous behavior is not entirely surprising. Lightning bugs are, after all, highly carnivorous, feeding on other arthropods, snails, slugs and worms.

By drawing attention to themselves with bright light, you might expect these creatures to be easily found and eaten by other predators. But the light is actually a warning—and it may have first evolved just for that purpose, only to be adapted later for mating rituals. Most glowing insects taste unpleasant, and many contain compounds that are toxic if consumed. Not to worry, however; any lightning bugs found in the U.S. are fairly harmless unless you’re planning on eating them!

The young of some lightning bug species can glow just like their parents, and these larvae are sometimes referred to as “glow-worms,” although the name is best reserved for another closely related family of glowing insects.

Lightning bug larvae usually grow up near wetlands or swampy areas. They winter over by burying themselves in the soil, and it may take several winters before they become adults.

From the June 28-July 4, 2006, issue

Enjoy The Rock River Times? Help spread the word!