How Fireflies Glow -- And What Signals They're Sending

How Fireflies Glow -- And What Signals They're Sending

You might not really be sure you saw what you think you saw when the first one shows up. But you stare in the direction of the flicker of light and there it is again – the first firefly of the evening. If you are in good firefly habitat, soon there are dozens, or even hundreds, of the insects flying about, flashing their mysterious signals.

Fireflies – alternatively known as lightning bugs in much of the United States – are neither flies nor bugs. They’re soft-winged beetles, related to click beetles and others. The most dramatic aspect of their biology is that they can produce light; this ability in a living organism, called bioluminescence, is relatively rare.

I’m an entomologist who does research on, and teaches about, the ecology and biology of insects. Recently, I’ve been trying to understand the diversity and ecology of fireflies in my home state of North Carolina. Fireflies are found widely across North America, including many places in the west, but they are most abundant and diverse in the eastern half of the continent, from Florida to southern Canada.