Why do fireflies flicker synchronously?

Why do some fireflies flicker synchronously? At the beginning of summer, in the Smoky Mountains region of the United States, male Photinus carolinus fireflies perform an unusual show to their female counterparts: they shine repeatedly and synchronously to illuminate the night sky. The reason for this synchronization has been a mystery for many years, but a new study may provide an answer.

Researchers know that fireflies usually use their flicker to find their mates, and each species has its own flicker pattern. So they investigated whether synchronous flicker of male P. Carolinus could help females identify the flicker pattern of their potential mates.

The researchers placed female fireflies in Petri Dishes, surrounded by LED lights that simulated male P. carolinus flickering patterns. These females respond more consistently to synchronous flickers (rather than those that do not). In their paper, the researchers concluded that these synchronized flickers could help females identify males who move around the environment. The authors suggest that since multiple flickering males are likely to appear in a female’s field of vision, synchronized flickering can help females find potential mates among these males without visual distraction.