Volume XXIX Number 1 Page 24

By Nancy C. Hinkle
University of Georgia

Fireflies, or lighting bugs, as they're commonly known, are neither flies nor bugs. They're beetles.

As spring evenings warm, fireflies arrive to entertain us with their courtship performances, remaining until the chill of winter kills them off. They're not only pleasant reminders of childhood play but a reassurance of environmental health as well.

These nocturnal fliers have light-producing organs at the rear of the abdomen. Within these structures, two chemicals combine to produce light in a process that's virtually 100-percent energy efficient, so no heat is generated. The resulting light may be greenish, orange or yellow.

Cruisin'

Georgia's lightning bugs start flying on warm spring evenings. The fireflies patrolling are males, scanning for mates. In their courtship, females sit on vegetation and send out their light signals, which males cue in on.

Each firefly species has a distinctive flash pattern, lasting for a specific time and with a definite interval between pulses. This allows the sexes to identify one another.

In a deceptive strategy, some female fireflies mimic other firefly species' flash patterns, luring in foreign males. These predatory females then eat the hapless males. Male fireflies feed on nectar and pollen.

Glimmer, glimmer

Firefly larvae generate light, too. They're called glowworms. Looking like aliens from outer space, these flattened, soft-bodied creatures have broad plates down their backs.

Because they're susceptible to dehydration, glowworms gravitate to moist areas, especially low-lying spots around streams and marshes.

On dark nights, glowworms may be seen crawling in leaf litter or rotting logs. They feed on slugs, snails and earthworms, injecting a toxin that paralyzes prey several times larger than themselves.

Yuck

Children who catch fireflies often notice a distinct odor left on their hands after the lightning bug is released. The beetle produces this chemical to repel predators.

Georgia has several dozen firefly species, ranging from less than half an inch to almost an inch long. Our most common species are black or gray with white, yellow and red markings.

Because each species has its own flight style and flash pattern, anyone can study and identify the different species inhabiting an area.

One species flies very high, dancing among the treetops. Another flies just out of human reach, dipping in a J-shaped swoop as it flashes. On rainy evenings, tiny woods-inhabiting fireflies mimic fairy lanterns bouncing around in knee-high flight.

(Nancy Hinkle is an Extension Service entomologist with the University of Georgia College of Agricultural and Environmental Sciences.)