Spatiotemporal patterns of flash synchrony in firefly mating swarms

On a midsummer night, firefly swarms might appear as a cloud of uncorrelated sparks, but they likely present a structured internal dynamics, shaped by evolution to optimize mating outcomes. As a blatant example of collective behavior, some species spontaneously synchronize their flashes, and at high density they create large-scale displays of blinking lights with complex correlations. Using stereoscopic reconstructions of swarms, we investigate how individual flash motifs and the structure of social interactions induce collective flash patterns of various kinds. We focus on two different species exhibiting either continuous or intermittent synchrony with an emergent frequency. Finally, we use the analysis of 3D trajectories to reveal social differentiation, information propagation, and broadly explore the interplay between movement and flashing behavior.