Why bees swarm and how to help maintain a healthy population

Spring and early summer are popular months for moving, and honeybees are no exception. Swarm clusters – the proper term for those humming, pulsating, large masses of bees that can suddenly appear on a random tree, fence, or other structure – can be intimidating and somewhat alarming. These clusters can consist of tens of thousands of bees, or they can be just (!) a few thousand. Any way you look at it, that’s a lot of bees!

When bees are on the move, they tend to be less aggressive since they aren’t defending a hive and they are probably just tired (moving is exhausting for bees, too). This does not mean that you can get away with throwing rocks at or spraying them with a hose. Everyone has their limits.

When you see a swarm hanging out in a tree or on a fence, rest assured that they will likely be on their way in a day or two. Most of the workers and their queen will take their rest while a few workers venture out to find a suitable place to build a new hive. Once they have found it, they return and lead the rest away to their new home.

Hopefully, the new home is an out-of-the-way hollowed-out tree and not your attic, chimney, irrigation box, garden shed, or interior walls.

If the swarm is hanging out on the side of a building and appears to be shrinking in size but not leaving, they may be busy establishing a hive inside that building. Keep this in mind if that building happens to be your house.

Relocating a hive is much easier when it’s just getting started. Don’t wait to seek help until the hive is established and everyone’s settled in. Some beekeepers will relocate hives, but if the hive is too big the process can become very difficult and expensive. In many cases, you will have no alternative but extermination.

Why do bees swarm? In most cases, it’s because the colony has gotten too big and needs to split. A portion of the workers leave, along with the old queen, and a new queen develops to take over the old hive. Sometimes the entire hive will relocate if there is a shortage of food, water, disease or pesticide exposure.