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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.)
