Synchronous Flashing in Fireflies

The wings are on and it’s starting to look more like the real thing.

Some male fireflies flash in sync over large areas. This species is apparently the only in the United States that does it. They can light up whole forests or hillsides with waves of synchronous display.

I found a recent explanation of the phenomenon here, but I’m not sure I understand it fully. Males fly around flashing to attract the females’ attention. The experiment showed that the females’ response rate was 10% or less with asynchronous flashing but over 80% if in sync. And if I’m reading it correctly, this suggests that it’s easier for females to track the movement of specific males when in sync, since out of sync “the female would see a cluttered landscape of unrecognizable flashes”.

I got to see some synchronous flashing myself last month. Japan’s GenjiBotaru does it too, though it wasn’t over a large area. I saw gangs of five to ten fireflies flying in groups and flashing in perfect sync. Lucky, since I was planning to incorporate it into my story.