Honey bee swarming is a natural process where a single colony divides into two separate, independent colonies, functioning as the primary method of reproduction for the species. The sight of tens of thousands of bees flying in a dense cloud is a carefully orchestrated migration, not an aggressive attack. This process ensures the survival and expansion of the species, allowing colonies to spread and adapt to new environments.
The Primary Motivation: Colony Reproduction
The main trigger for a honey bee colony to swarm is the internal pressure of rapid population growth and resulting congestion. Swarming typically occurs in the spring or early summer when foraging resources are abundant, allowing the colony to reach its maximum size. When the hive becomes overcrowded with adult bees, brood, and stored resources, the existing queen and worker bees receive chemical and physical signals that initiate the reproductive split.
Overcrowding leads to a decrease in the concentration and transmission of queen pheromone throughout the hive, which normally inhibits the workers from raising new queens. In response to this diluted signal, workers begin constructing specialized, larger queen cells. The reigning queen lays eggs in these cells, and the larvae are exclusively fed royal jelly, allowing them to develop into new queens.
Once these new queen cells are capped, signaling the imminent emergence of a successor, the original queen prepares for departure. The old queen leaves with approximately 40 to 70% of the worker bees to establish a new home. This departing group ensures the perpetuation of the colony’s original genetics, leaving behind the remaining population, developing resources, and the soon-to-emerge virgin queens.
The Mechanics of the Swarm
Before the mass exodus, the old queen reduces her egg laying and slims down, preparing her body for sustained flight. Worker bees that will join the swarm gorge themselves on honey to fuel the journey and provide initial energy for building comb at the new location.
The departure is a sudden event, often lasting only a few minutes, where thousands of bees lift off simultaneously. The massive cloud flies a short distance and congregates on a temporary site, such as a tree branch or structure, forming a tight, hanging cluster called a bivouac. During this clustering period, the bees are docile because they are far from their established nest and have no brood or large stores of honey to defend.
While clustered, specialized scout bees continue to assess potential permanent nest sites. These scouts perform waggle dances on the surface of the cluster to communicate the direction, distance, and quality of a potential site. The swarm uses a collective decision-making process, often requiring a quorum of scouts to agree on the best location before the entire group takes flight again, sometimes traveling up to a few miles to their final destination.
Absconding: Swarming Under Duress
Absconding is a mass movement triggered by severe stress or environmental duress, not reproduction. It represents the complete abandonment of the current nest site. When a colony absconds, the entire population, including the queen, leaves the hive to seek a more suitable location, resulting in an empty or nearly empty hive.
The primary causes of absconding are external threats or resource scarcity. These stressors include a severe lack of forage or stored food, extreme temperatures, or inadequate ventilation within the hive. Overwhelming infestations of pests, such as Varroa mites or wax moths, or significant disease outbreaks can prompt a colony to abandon its home entirely.
Absconding colonies often prepare for their departure in advance by consuming most of their resources and ceasing egg-laying, much like a reproductive swarm. However, unlike swarming, the remaining structure is left with little to no brood or food, and the colony does not split; instead, the entire organism moves. This behavior is more common in tropical honey bee subspecies, which use migration as a strategy to survive harsh dearth periods.
Public Safety and Intervention
Swarming bees are usually at their least defensive state. Since they carry full honey stomachs and have no established home or young to protect, they are focused solely on resting and locating a new nest site. They will not sting unless they are directly provoked, crushed, or aggressively disturbed.
If a swarm cluster is found in a public or residential area, maintain a safe distance and avoid disturbing the bees. Never attempt to spray the cluster with water or pesticides, as this will agitate the bees and provoke defensive behavior. The swarm is often temporary and may relocate on its own within a few hours or a day once the scout bees have finalized a new home.
The appropriate intervention is to contact a local beekeeper or a specialized swarm collector who can safely capture and relocate the bees. Most beekeeping associations maintain lists of members who collect swarms for population management and to prevent the bees from establishing a nest in an undesirable location. Calling a professional is the safest course of action, ensuring both public safety and the protection of the honey bee colony.