Understanding the reason that bees swarm requires understanding a bit about bee biology. Bees are what is called eusocial meaning that they do not see themselves as individuals but as the very colony in which they live. An example of this can be seen in how they distribute food throughout the colony. If there is a food shortage, rather than take sides or split into groups to fight over it, they distribute it evenly. If the colony is going to die due to lack of food, then they are going to die together. Honey bees are the very definition of synergy.
Swarms generally occur in the late spring and early summer months. The conditions within the hive will likely be crowded. Cells are filled with capped honey and pollen stores as well as eggs and larvae in various stages of development. As the warm weather hits and flowers begin to blossom, any empty cells are filled with the nectar that will become honey. With as many as 15,000 new bees emerging in a week it doesn’t take long for the bees to run out of room.
The life cycle of the honey bee is about six weeks meaning that if there is no place for the queen to lay new eggs, after six weeks the colony will die. The bees know that the survival of the colony depends being able to reproduce the colony as a whole. When they sense that they cannot expand the colony under present conditions they prepare for the move to a new home.
Stored honey is cleaned from the cells with each bee collecting as much food as they can carry. Then, to lighten the load on the egg-heavy queen enabling her to fly, they chase her around the hive encouraging her to lay eggs in the now empty cells. Worker bees create specially constructed queen cells where the current queen will lay eggs that will be tended by the remaining bees, hopefully raising a new queen and a new colony.
The queen, surrounded by as few as 2,000 or as many as 30,000 to 40,000 workers takes flight, usually to land in a nearby tree not far from the hive. The workers swarm around her, linking arms to form what appears to be an undulating ball hanging from the tree. Scout bees take off looking for a new place to call home. When they return, they communicate their findings (size, distance, location, angle to the sun) to the rest of the swarm through what is called a waggle dance. The more information communicated through the excited dance, the more the colony takes notice and will move en masse to the new home.
If the new home is a hollowed out tree, the bees have a lot work to do drawing new honeycomb to hold precious food, eggs and larvae before they can settle in. Since only the youngest bees can produce the wax needed for comb and it takes three weeks for a egg to mature into an emerging bee, this can take some time and the survival of the colony hangs in a precarious balance.
The savvy beekeeper can capture the swarm by placing an empty wooden hive on the ground below the cluster. It’s a bonus for the bees if the frames within the hive already contain drawn honeycomb as the colony can get right to work filling the cells, expanding the hive and producing sweet and delicious honey.
I would have preferred the placing the hive under the swarm method to my actual experience of climbing a ladder to capture a swarm by hand. In the early summer of 1981 my father, a beekeeper, had broken his ankle and was unable to do much on crutches. So, under his direction, I was elected to don the bee suit, haul the ladder, place it against the tree, climb up as close as I could get to the branch holding the swarm and then using a hand saw, cut the branch holding the swarm from the tree.
I was terrified. The bees, however, were not the swarming mass of darting, stinging anger I had expected. Instead, they were heavy and slow and almost fluid in how they moved together. As the last few strokes of the saw freed the branch from the tree, I held the full weight of the swarm in one hand. Seeing and hearing the bees was one thing but with the branch held tightly in my hand I could now feel the buzzing fluidity resonating through my arm and into my body.
I carried the swarm to the empty hive my father had prepared and gently shook the bees onto the tops of the frames. Feeling confident that the queen bee was within the mass that fell from the branch I covered the hive and placed the branch, still covered with a significant amount of bees on the ground near the hive opening. I had done it.
What had seemed terrifying in my mind was actually quite a pleasant experience. To do it, I had to get over my fears, one by one, and just keeping following my fathers direction in taking the next step. Before I knew it, the job was finished and I had survived without so much as even one sting.