New Beekeepers who are successfully over wintering hives for the first time are likely to see their overwintered colonies build up strongly on the early spring nectar flows.
Unfortunately strong overwintered colonies have a natural tendency to reproduce by swarming.
A new honey bee colony is formed when the queen bee leaves the colony with a large group of worker bees, a process called swarming. In the primeswarm, about 60% of the worker bees leave the original hive location with the old queen.
Swarming (honey bee) – Wikipedia, the free encyclopedia