Mating between the drones and a virgin queen takes place away from the colony, in mid-air mating sites. These mating sites, called ‘congregation areas’, are specific locations, where drones wait for the arrival of virgin queens. A congregation area is typically 10–40 m above ground, and can have a diameter of 30–200 m. The boundaries of a congregation area are distinct; queens flying a few meters outside the boundaries are mostly ignored by the drones. Congregation areas are typically used year after year, with some spots showing little change over 12 years. Since drones are expelled from a colony during the winter, and new drones are raised each spring, inexperienced drones must find these congregation areas anew. This suggests some environmental cues define a congregation area, although the actual cues are unknown.