Why Colonies Swarm
Swarming is the natural reproductive process for a honey bee colony, serving as the biological mechanism by which a single colony divides itself to create two distinct new ones. This event is triggered primarily by internal conditions within the hive, signaling growth and abundance.
The primary physical trigger for a swarm is colony overcrowding and a lack of space for the queen to lay eggs and for the bees to store nectar and pollen. As the population swells, typically during the heavy nectar flow of spring, the internal congestion increases, causing a reduction in the distribution of the queen’s pheromone. This chemical signal, which normally maintains colony cohesion and suppresses the workers from raising new queens, is no longer effectively circulated throughout the entire hive.
In response to the diminished queen pheromone, worker bees begin constructing specialized, peanut-shaped queen cells, often along the bottom edges of the brood frames. The existing queen deposits eggs in these “swarm cells,” which workers provision with royal jelly to raise new queens. Simultaneously, workers prepare the old queen for flight by significantly reducing her food intake. The swarm, which includes the old queen and about half to two-thirds of the adult worker population, departs the original nest just before the first new queen emerges from her cell.
The Phases of Swarming
The moment of departure begins with a massive number of bees pouring out of the hive entrance in a swirling, audible cloud. This initial phase can involve tens of thousands of bees taking flight simultaneously. They remain airborne for a brief period, swirling near the original hive until the queen settles on a temporary staging area, often a low tree branch, fence post, or shrub.
Once the queen lands, worker bees rapidly cluster around her, forming a dense mass of interlocked bodies that protects her and conserves heat. This temporary cluster, or bivouac, is a resting and decision-making phase that can last anywhere from a few hours to several days. The bees remain docile because they have no brood or resources to defend, and their digestive tracts are full of honey consumed before leaving the parent hive.
While the majority of the swarm is clustered, a small contingent of 20 to 50 specialized scout bees flies out to search for a new, permanent nest cavity. These scouts inspect potential locations, looking for a dry, dark cavity with a small entrance and an internal volume of around 40 liters. Upon returning, successful scouts communicate the quality, direction, and distance of their find using a complex “waggle dance” performed on the cluster’s surface. Through consensus, the swarm selects the best site, and the entire cluster takes flight again, moving directly to their final destination to begin building comb.
Encountering a Swarm
If you encounter a cluster of bees, remember that swarming bees are at their most docile and pose very little threat. Because they have abandoned their old home and have not yet established a new one, they have no comb, brood, or stored food to defend, making them non-aggressive. Their primary focus is on protecting the queen and conserving the energy needed for the final flight to their new home.
Maintain a distance of at least 30 feet and observe the spectacle without disturbing the cluster. Avoid provoking the bees by throwing objects, spraying water, or attempting to break up the cluster. These actions can cause the bees to become defensive, increasing the risk of stings.
Do not attempt to apply pesticides or other chemicals to the swarm, as this is ineffective and can be harmful to beneficial pollinators. If the swarm has settled in a location that presents a risk, such as near a doorway or playground, the correct next step is to contact a local beekeeper or beekeeping association. These specialists are trained to safely capture and relocate swarms without harming the insects, often providing them with a new hive home where they can thrive.
If the swarm is near small children or pets, keep them away from the immediate area, as curiosity might inadvertently disturb the bees. Though swarms are gentle, any disturbance could lead to a defensive reaction. A beekeeper should be contacted immediately for safe removal, ensuring the safety of both the bees and the residents.