To achieve this concentration she must mate with several drones - at least seven, maybe many more. The virgin does not fly haphazardly about hoping by sheer chance to encounter drones. She goes directly to drone congregation areas. Exactly why drone congregation areas originate where they do is not fully understood, but the same areas are used year after year. The drones within any congregation area come from many different colonies, and probably several different apiaries.
Drones have a flight range of up to six kilometers with flights of five common.
Thus drones can range over an area of roughly 78 square kilometers. It has been shown that virgins very rarely mate with related drones, which reduces the chances of inbreeding, one of the perils to avoid in any controlled breeding scheme. Thus, if we allow virgins to mate naturally, we have no control over the drones. Even with isolated mating yards, control is not absolute. To compound this there are multiple matings.