Fluid mediated self-organization of ventilation in honeybee nests

European honey bees (Apis mellifera) live in large congested nest cavities with a single opening that limits passive ventilation. These nests are actively ventilated by individual bees which fan their wings at the nest entrance when the local air temperature exceeds a threshold. Here we show that colonies with relatively large nest entrances use an emergent ventilation strategy where fanning bees self-organize to form fanning groups, separating regions of continuous inflow and outflow. The observed spatio-temporal patterns correlate the air velocity and air temperature along the entrances to the distribution of fanning bees. A mathematical model that couples these variables to known fanning behavior of individuals recapitulates their collective dynamics. Additionally, the model makes predictions about the temporal stability of the fanning group as a function of the temperature difference between the environment and the nest. Consistent with these predictions, we observe that the fanning groups drift, cling to the entrance boundaries, break-up and reform as the ambient temperature varies over a period of days. Overall, our study shows how honeybees use flow-mediated communication to self-organize into a steady-state in fluctuating environments.