Swarm Facts

        As the days get longer and the temperatures get warmer, honey bee activities begin to increase as they prepare for the spring nectar flows. The bees are now beginning to build up their populations in order to have enough worker bees to gather the nectar. As the populations build up, some bee colonies increase their numbers very quickly and some individual hives may become overcrowded. These overcrowded conditions can stimulate a phenomenon called "swarming".

        Swarming is part of the reproductive cycle in honey bees. Though honey bees reproduce individual bees through mating and egg-laying, swarming is how honey bees create new colonies. The process of swarming involves production of a new queen within an individual colony. When this queen emerges and is ready to take on the duties of a queen bee, the old queen (the new queen is now the queen of the old hive), along with approximately one-half of the workers in that colony, will leave the hive as a large mass of bees. This mass of bees will congregate on a tree limb, fence post or on a side of a building near the original hive. A congregation of bees in this manner is called a swarm. (Some colonies will swarm several times, so some of these swarms will have new queens.)

        While the bees are in this swarm, some workers are sent out to search for a suitable place to start a new hive. We call these particular workers "scouts". When some of the scouts have found a favorable site for a new hive (such as a hollow tree), they report back to the swarm and then the swarm leaves the swarming site to go to the new hive.
        Swarming season, in York County, can begin in April and can last through the first of July. Some of you may have the opportunity to find a swarm this spring. You may find a clump of bees that can range from about the size of a softball to as large or larger than a basketball. You may find them on a tree limb, in a shrub, on a fence post or on the side of a building. If you find a swarm, the best thing that you can do is leave it alone. Honey bees, that are in a swarm, are not aggressive because they have no hive to defend at this time. These bees, however, should only be handled by an experienced beekeeper.

        Swarms may stay on a swarming site for as little as 15 minutes or for several days or more. It depends on the length of time it takes for the scouts to find a new hive. So when you see a swarm, keep in mind that they will not be on that site permanently.

        Spraying honey bee swarms with insecticide is not recommended for several reasons. First of all, even though the bees are not aggressive during swarming, you run the risk of getting stung if you try to spray them. Secondly, the bees are only going to be there for a short period of time, so spraying them will be a waste of your time. Finally, if the swarm is reachable, the bees are valuable to a beekeeper. If a swarm is found before it locates a new home, a beekeeper can capture the swarm and start a new hive with the bees.

Swarm FAQs

What is a honey bee swarm?
Honey bee swarms are a favorite topic of people who make horror movies. Actually, they are one of the most beautiful and interesting phenomena in nature. A swarm starting to issue is a thrilling sight. A swarm may contain from 1,500 to 30,000 bees including, workers, drones, and a queen. Swarming is an instinctive part of the annual life cycle of a honey bee colony. It provides a mechanism for the colony to reproduce itself.

What makes a honey bee colony swarm?
Overcrowding and congestion in the nest are factors which predispose colonies to swarm. The presence of an old queen and a mild winter also contribute to the development of the swarming impulse. Swarming can be controlled by a skilled beekeeper; however, not all colonies live in hives and have a human caretaker.

When do honey bees swarm?
The tendency to swarm is usually greatest when bees increase their population rapidly in late spring and early summer. Typically, this would be April through July.

Are honey bee swarms dangerous?
No - honey bees exhibit defensive behavior only in the vicinity of their nest. Defensive behavior is needed to protect their young and food supply. A honey bee swarm has neither young nor food stores and will not exhibit defensive behavior unless unduly provoked.

What should homeowners do about a honey bee swarm on their property?
When honey bees swarm they will settle on a tree limb, bush, or other convenient site. The cohesiveness of the swarm is due to their attraction to a pheromone produced by the queen. The swarm will send out scout bees to seek a cavity to nest in and will move on when a suitable nesting site is found. Rarely, swarms may initiate comb construction in the open if a suitable cavity cannot be found.

How does a beekeeper go about capturing a swarm of honey bees?
A swarm is looking for a new nesting site. A beekeeper can capture a swarm by placing a suitable container, such as an empty beehive, on the ground below the swarm and dislodging the bees at the entrance to the hive. The bees will begin to move into the hive which can be removed after dark to the beekeeper's apiary. You can observe the bees scent-fanning at the entrance to signal the entrance to the new nest as the bees march into their new home. If for some reason the queen does not go into the new hive, the bees will abandon it and form a cluster where she lands.

What type of nesting sites will honey bees seek?
Honey bees are cavity nesters and will seek a cavity of at least 15 liters of storage space. Hollow trees are a preferred nesting sites. Occasionally, bees will nest in the hollow walls of buildings, under porches, and in other "man-made" sites if they can find an entrance to a suitable cavity.

What can be done if a honey bee swarm establishes itself in an undesirable place?
Honey bees are beneficial pollinators and should be left alone and appreciated unless their nest are in conflict with human activity. If honey bees nest in the walls of a home, they can be removed or killed if necessary; however, it is advisable to open the area and remove the honey and combs or rodents and insects will be attracted. Also, without bees to control the temperature, the wax may melt and honey drip from the combs. After removal, the cavity should be filled with foam insulation as the nest odor will be attractive to future swarms. You may want to seek the assistance of a professional beekeeper or exterminator. Nests should be removed promptly from problem sites. After several months, they may have stored a considerable amount of honey. You can prevent swarms from nesting in walls by preventive maintenance. Honey bees will not make an entrance to a nest. They look for an existing entrance, so periodic inspection and caulking is all that is necessary to prevent them from occupying spaces in walls.