Blinking fireflies are icons of Georgia summer nights

I visited the Fernbank Museum of Natural History last weekend to see its special exhibition, “Creatures of Light: Nature’s Bioluminescence,” and learn more about the extraordinary organisms that produce their own light — from glowing mushrooms and insect larvae to ocean-inhabiting fluorescent corals and vampire squid.

Most of my attention, though, was focused on the bioluminescent creatures that we in Georgia know best, fireflies.

Using larger-than-life models and other aids, the exhibition (which runs through Aug. 14) explains in fascinating detail how the night-flying fireflies, which actually are beetles, blink their lights to lure mates and warn off predators.

Light-producing organs at the rear of their abdomens contain two chemicals — luciferin and luciferase — that are combined to generate light in a process that’s nearly 100-percent energy efficient, so no heat is generated. The light may be greenish, orange or yellow.

The show left me with a greater appreciation of the flashing insects. To many of us, fireflies — or lightning bugs — are icons of a Georgia summer night. Without flashing fireflies, summer evenings are not the same.

Georgia has more firefly species than any other state — 56 species, each having its own distinct flash. Males flash while flying; wingless females sit on vegetation and emit their own light signals, which the males cue on.

The other night, I sat on my Decatur front porch to see if any fireflies were blinking in the yard. I detected only five or six, but I was glad even for that small number.

Fireflies are declining all over the world. For several summers now, once-abundant fireflies have been scarce or absent altogether in many metro Atlanta neighborhoods.

Habitat loss due to development and pesticide misuse probably are some reasons. Also, since fireflies use light to communicate, too many bright lights at night — street lights, outdoor signs, porch lights — may confuse the insects and make it harder for them to find a mate.

In the sky: From David Dundee, Tellus Science Museum astronomer: The moon will be last-quarter Monday. Mercury is low in the east just before sunrise. Mars is in the south, Jupiter is low in the southwest and Saturn is in the east at nightfall.

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