The science of how fireflies stay in sync
The team found that even small numbers of interacting males can synchronize their flashes, but that the periodic bursts only occur in groups of more than 15. And the flashes are correlated over several meters, evidence of long-range interactions typical of emergent collective behavior. But Peleg et al. also noted some individual trajectories, suggesting that there might also be other competitive mechanisms at play: for example, early flashing fireflies appeared to be more mobile and flashed longer than later fireflies.
Collective exhibition of Photinus carolinus fireflies recorded in the Great Smoky Mountains National Park in early June 2019.
Peleg’s lab has since built on this previous research. The latest findings are the result of field work conducted every May for four years (2021-2025) in South Carolina’s Congaree National Park. Once again, they installed a pop-up tent isolated from external light sources. Then, they exposed the captured fireflies to a dim LED light that mimicked a firefly flash, flashing between once per second and once every 300 milliseconds.
The results: Fireflies were more likely to change their own blinking rhythm in response when the LED flashed almost, but not quite, at the same time as the fireflies. Males sped up their next flash if the LED flashed just before and waited a little longer for their next flash when the LED flashed right after. The authors compared it to an audience member in a crowded concert hall trying to clap along to the beat in sync with everyone else.
“For an entire season, I spent almost every night in the dark watching the lights flash at a fixed frequency,” former graduate student (and co-author of the preprint) Owen Martin said of the field observations. “Then, every now and then, I would have this magical experience where I would see the firefly start to synchronize with the light. I wondered if I was just seeing things.” But the mathematical analysis that followed confirmed the patterns: the dynamics of individual flashes essentially followed a phase response curve, which the authors then used to develop an “integrate and fire” model that accurately reproduced the observed synchronized flash patterns.
DOI: bioRxiv, 2026. 10.64898/2026.01.19.700439 (About DOIs).
