This is possible because all the bees in a colony have a common smell.
This smell acts like a chemical signal.
It warns the group of bees when a bee from a different a colony is near.
This way, bees from outside cannot enter and disturb a have (the bee colony' s home).
If an outsider does try to enter, the bees of that colony will smell it and attack it.
Communication is also possible among bees through their sense of smell