How Do Fireflies Sync Their Flashes?

Imagine a room full of people clapping. At first, everyone claps at their own speed and rhythm. But if they watch each other closely, they start to clap together. Eventually, the whole room makes one big sound. Fireflies do something similar with their lights.

Each firefly has a tiny light inside its body that turns on and off like a flashlight. They do not have a boss telling them when to flash. Instead, they use their eyes to see what their neighbors are doing. If one firefly sees another flash just before it was about to flash itself, it speeds up its next flash slightly. If the neighbor flashes too early, the first firefly waits a little longer.

Over time, these small adjustments cause nearby fireflies to flash at exactly the same moment. This pattern spreads through the group like a wave moving across a field of grass. By the end, thousands of fireflies create one giant light show for just a few minutes every night.