To mate, the queen leaves the hive and flies to a drone congregation area where she meets drones high in the air. By the time she returns to the hive, her sting chamber is filled with a 'mating sign' (Fig. 1 a, b). This mating sign consists of mucus from the male accessory glands and the expelled chitin plates of the drone's endophallus. Because this secretion completely fills the sting chamber, it has been regarded as evidence for monogamy* in the honeybee.