Episode 17: Whenever a threat appears near a hive, dozens of bees assemble to draw it off. These bees warn each other of the danger by emitting alarm pheromones, hence their synchronisation. Scientists from Toulouse decided to study bees' brain activity to better understand this behaviour. They discovered that some bees are more aggressive than others, but also that detecting alarm pheromones increases the aggressiveness of all bees, even the calmer ones. This study could help beekeepers keep the hives under control.