A peaceful form of summer entertainment is sitting out in the yard watching fireflies do their light show at dusk. And who hasn’t as a child stalked and captured “lightnin bugs” in a jar? Fireflies are real standouts of the insect world, so let me illuminate you (yes, humor).

There are over 2000 species of fireflies on the planet, and our local representative is the Common Eastern Firefly (Photinus pyralis). They are easy enough to identify at night, but in daylight they are ¾ inch long beetles with black wings and a red area near the head with a black spot in it. It’s the male you see flying and blinking at night, as the female mostly stays on the ground, even though she has wings.

To cover the life of the firefly, let’s start with the bling… the winking yellow light. While we enjoy the light show readily enough, the male’s real end game is to get the attention of a female sitting on the ground looking up at him. The light signal varies among species, but ours traces a J shape. The male will hover, then drop suddenly and flash near the bottom of his fall and then swoop back up, letting the light slowly fade as he rises. If a female likes what she sees, she responds by flashing at a specific rate after the male’s last flash. A short flash dialogue may ensue (a form of flirting I suppose), helping the male locate her position so he can descend to mate. Flashing of the eastern firefly is most active at dusk, which is earlier than most other species. Also, their flash is yellow, while other species emit green.

A few days after mating, a female lays her fertilized eggs on or just below the soil surface. They hatch in 3-4 weeks as larvae (called glowworms), which spend the rest of the summer underground hunting and feeding on earthworms, other insect larvae, slugs, and snails. After overwintering, they resume feeding in the spring and eventually pupate and emerge as adults to start the cycle over.

Organic chemists are really into fireflies because the glow is produced by a chemical reaction (called bioluminescence) that produces essentially no heat. It is so efficient that 90% of the energy expended is converted to visible light. By comparison, the best we humans can do is the L.E.D. light, which only converts 20% of the total energy used to light. The chemical reaction occurs in something called a photic organ located on the abdomen. The process is complicated, but in a nutshell when an enzyme called luciferase reacts with something called luciferin, you get light.

Tropical fireflies routinely synchronize their flashes among large groups, called biological synchronicity by the science guys. A few places in the United States also have this occurring, most notably at Elmont in the Smoky Mountain National Park, where they will suddenly all blink in unison. It’s a show that draws quite a crowd, so much so that to have a shot at seeing them you must enter a lottery draw.