Firefly Flashes Are Light Signals

In many fireflies, flashes form part of a courtship “dialogue”: males produce a species-specific signal, and females answer after a characteristic delay. Flash duration, number, and rhythm can help individuals recognize potential mates. But this is not how every species signals, and some fireflies even mimic other species’ signals. Bioluminescence emits light very efficiently with little heat; laboratory measurements of the chemical reaction have found a high quantum yield, though that is not the same as saying a fixed share of all bodily energy becomes light.