When do bees sting and how do they organize their collective defense behavior against predators? An interdisciplinary team of researchers from the Universities of Constance and Innsbruck has provided new insights into these questions. Their study, published in BMC Biology, combined behavioral experiments with an innovative theoretical modeling approach based on projective simulation. It shows that individual bees decide whether to sting—or not—based on the presence and concentration of an alarm pheromone. The scientists suggest that each bee has a likelihood of stinging that is not constant, but shows at least two internal thresholds for the concentration of the pheromone: one to start stinging and one to stop stinging. The computational modeling also revealed how several environmental factors, such as the rate of predator attacks and predator diversity, likely drove the evolution of the honeybees' pheromone-based communication in their defensive behavior.