Utah State University Extension
Warming late spring temperatures mark the beginning of swarm season in Utah, especially for beehives that have successfully overwintered. Swarming is when bees naturally divide the existing colony roughly in half, with half the bees remaining in the hive and the other half leaving (with the queen) to look for new accommodations. Colonies that swarm are often left with limited resources, do not produce much honey, and can be rendered too weak to overwinter. Splitting your hives in anticipation of swarming can help reduce the negative effects of swarming, giving bees a chance to build up resources and strength before the next winter. This fact sheet explains how to split hives, which is a better alternative than swarming that can prove detrimental to colony strength and longevity.
Hansen, Sheriden M.; Walker-Bravo, Andree; and Gunnell, Jaydee, "Splitting the Hive" (2020). All Current Publications. Paper 2103.