Fireflies (or "lightning bugs," as we sometimes call them) are seemingly magical creatures that put on dazzling displays of light. They appear in the largest numbers around sunset, but their greenish glow makes they unmistakable when the Sun completely disappears from the sky. Where does this glow come from? And how does it manifest itself?
In most cases, organisms with the capacity to render light through biological processes do so using something called chemiluminescence. The specifics aren't the same for all bioluminescent creatures, but the bottom line is this: bioluminescence normally involves luciferin and luciferase (the former produces the light, while the latter is the catalyst for the reaction).
With fireflies, the answer doesn't appear to be that simple. In a new video, the American Chemical Society explains,