The old farmers always said:
Honey bees often swarm in the spring and early summer, May and June here in Iowa. When their population increases rapidly and conditions inside the hive become too crowded. Prior to swarming, the bees will gorge on honey to fuel their flight. Then the queen and half the bees will take off in search of new digs. But before the swarm makes it too far from the hive it will take up temporary residence on something nearby - a bush, a tree branch, a picnic table, a fence, etc. - clustered together with the queen inside. The cluster of bees will stay put for a few hours up to a few days while scout bees search for a new home.
From the beekeeper's perspective, swarming is considered something to avoid because it drastically reduces the number of bees available to make honey. Some beekeepers who aren't as interested in harvesting honey but keep bees more for pollination services may view swarming as a helpful self-thinning event. But if the swarm leaves later in the year it can leave behind a colony too weak to make it through the winter. Ideally beekeepers try to prevent swarms.
We are heavy into the swarm season now, and for many beekeepers it's a great way to get free bees! You just need to keep extra equipment on hand to be ready to capture the swarm. Beau brought my bee veil on his way back for his last final exam of his Junior year. That and a pair of coveralls and a cardboard box was all I needed to capture the swarm.... Score.
4 hives from left to right. Last years captured swarm, this years swarm, this years 2 lb. package and one strong honey producing hive that's two years old.
If you observe a swarm on your property and would like someone to come get it you can contact me and i will be out asap.