Chimera states among synchronous fireflies

Mathematical models of coupled oscillators often exhibit a rich phase diagram. Among these phases, "chimera states" refer to the coexistence of synchronous and incoherent clusters in a population of identical oscillators. For the past two decades, they have received significant attention, notably for their apparent symmetry-breaking character. While abundant in models, chimeras have remained elusive in real-world settings. A few carefully designed experiments had produced physical chimeras, yet they had not been observed in nature.

We present evidence for the occurrence of chimera states within swarms of synchronous fireflies. Using 3D reconstructions of the swarms, we show that different groups flash with the same frequency but with a persistent delay between them. These subpopulations appear spatially intertwined, with only weak signatures of clustering or correlated velocity. We discuss the implications of these spontaneous, self-organized chimeras for the structure of firefly social interactions and future theoretical paradigms.