Toward the end of honey collecting period the population of colony is at a maximum. As the supply of nectar diminishes, the queen slows down her frantic pace of laying, the net effect is a reduced population. The bees maintain the population of drones as other colonies virgin queens may need them to mate. (Their queen may have run out of sperm or become too old). In late autumn the bees start killing the drones as they are a burden the food resources of the colony in the winter months. The activity of the colony dwindles and the royal jelly food source that was feed continuously to the queen during spring and summer is changed to a honey diet.
The change in diet causes her to stop laying and brood rearing finishes for another year. The number of occupants in the colony reduces to a minimal level giving the highest chances of surviving the cold winter months. Less bees mean that their precious stored food supply will last longer. If the colony is too weak though, they struggle to generate the heat needed to keep themselves warm often freezing to death over winter. It is very important that the bees accurately judge the right population for the winter period.
So the colony life cycle starts again. Further information on the honey bee development cycle.