The hive will always have guard bees on alert against the entry of robber bees from another hive, or predators such as ants.
Any bees approaching the entrance will be inspected to ensure they match the "hive odour" which is derived from the queen's pheromones.
Foraging bees which have become disoriented and approach the hive with a load of nectar will often be admitted and accepted by the hive.
In this way, a weak hive can be strengthened by swapping its position with a strong hive, so that foraging bees will orient to their original location, adding their numbers to the population.
When moving hives to access nectar sources, or because of problems with the site, it is essential to move the hives initially at least 3 kilometres so that the bees will then orient to their new location, rather than returning to an empty space.