Bee Mating and the drone reproductive organ

The drone penis is designed to disperse a large quantity of seminal fluid and spermatozoa with great speed and force. The penis is held internally in the drone (an endophallus). During mating, the organ is everted (turned inside out), into the queen.

The eversion of the penis is achieved by contracting abdominal muscles, which increases hemolymph pressure, effectively “inflating” the penis. Claspers at the base of the penis help to grip the queen. Mating between a single drone and the queen lasts less than 5 seconds, and it is often completed within 1-2 seconds. Mating occurs mid-flight, and 10-40m above ground. Since the queen mates with 12±7 drones, and drones die post-mating, each drone must make the most of his single shot. The drone makes first contact from above the queen, his thorax above her abdomen, straddling her. He then grasps her with all six legs, and everts the endophallus into her opened sting chamber.

If the queen’s sting chamber is not fully opened, mating is unsuccessful, so some males that mount the queen do not transfer semen. Once the endophallus has been everted, the drone is paralyzed, flipping backwards as he ejaculates. The process of ejaculation is explosive—semen is blasted through the queen’s sting chamber and into the oviduct. The process is sometimes audible to the human ear, akin to a “popping” sound. The ejaculation is so powerful that it ruptures the endophallus, disconnecting the drone from the queen. The bulb of the endophallus is broken off inside of the queen during mating—so drones only mate once, and die shortly after.

The leftover penis remaining in the queen’s vagina is referred to as the “mating sign”. The plug will not prevent the next drone from mating with the same queen, but may prevent semen from flowing out of the vagina.