In nature, honey bee colonies do not generally combine themselves. Rather, small, weak colonies are robbed of their stores and they subsequently starve as the seasons cools. However, a common beekeeper/assisted management scheme to to combine the weak colony with a slightly stronger colony. I sense that primarily, what is happening is that the beekeeper gets the equipment cleaned by the bees and wax moths entry is restricted. There does not appear to be much of a reward in the plan for the stronger colony.
