SUMMARYAn apparatus is described by which tethered virgin queens could be suspended for restricted flight at desired heights up to 11 m., enabling observations on mating. Drones were attracted in large numbers and seemed to show normal mating behaviour. Their flight near the queen is described in detail, and the methods by which they locate her. Drones, first attracted by the scent of queen sex attractants, approached from windward, flying typically in sparse swarms that assembled and hovered in conical formation below and behind the tethered queens. Drones were consistently observed to mount on top of the queen's abdomen, but successful mating followed rather rarely. Mating behaviour was very stereotyped; the drone clasped the queen's abdomen and everted the genitals into the sting chamber, which must be open. Paralysis of the drone accompanied the onset of genital eversion; this caused the drone to swing over backwards, attached by the genitals which everted more completely as the physical restraints inherent in the initial position were released. Finally, as the drone hung from the queen, the mating act was terminated by an audible snap, presumably caused by compressed air in the drone genitals, and apparently serving to separate the drone physically from the queen. Mating required only a few seconds, and in normal circumstances the entire act probably takes place in the air.Many free-flying drones were induced to ‘mate’ with queens in which an open sting chamber was simulated by the removal of segments 7–10, leaving an open body cavity. Lack of success in getting routine matings, using either the tethering technique or the release of free-flying queens, was probably due to failure on the part of the virgin queens to open their sting chambers.Drone behaviour must be considered carefully when conducting bioassays of sex attractants. Weakly attractive fractions are difficult to detect unless drones are attracted into the neighbourhood by a lure of crude queen lipid extract, or a tethered virgin queen.