Swarming is the natural process by which a honey bee colony reproduces, dividing a single large unit into two separate groups. It is a complex, highly coordinated behavior that unfolds over several weeks in a predictable sequence of steps. This division ensures the survival of the original home while establishing a new colony elsewhere. The process requires thousands of worker bees to shift their physiology and behavior in response to internal and external cues. The colony commits to swarming only after specific conditions align, guaranteeing the future of both the departing bees and the original hive.
The Environmental and Biological Triggers
The decision to swarm begins when the colony recognizes that its current size is no longer sustainable, often triggered by the rapid population growth of spring. Overcrowding is a primary physical factor, creating congestion in the brood nest and limiting space for the queen to lay eggs or for workers to store incoming nectar and pollen. This pressure is compounded by the seasonal timing, as swarming typically coincides with the spring bloom when resources are abundant, signaling that a newly formed colony can establish a home successfully.
A change in chemical communication provides the biological signal for swarming preparations. The queen produces the Queen Mandibular Pheromone (QMP), which suppresses the workers’ urge to raise new queens and maintains colony cohesion. When the hive population becomes too large, the effective distribution of this pheromone is reduced. This drop in QMP signaling, or a similar reduction caused by an aging queen, alerts the workers that the time for colony division has arrived.
Initiating the Succession Plan
The first definitive action taken by the workers is the commitment to raising a successor for the original hive. This involves the construction of specialized queen cells, which are distinct from the smaller, hexagonal cells used for worker or drone brood. These structures are built vertically and are typically located along the bottom edges of the honeycomb frames.
Worker bees carefully select young female larvae, usually less than three days old, that have been laid in these new cells. The selected larvae are fed copious amounts of Royal Jelly, a protein-rich secretion from the nurse bees’ hypopharyngeal glands. This specialized diet triggers the genetic pathway that leads to the development of a fertile queen rather than a sterile worker bee. By raising multiple new queens, the original colony ensures the survival of its genetic line before the current queen and her accompanying swarm depart.
Preparing the Prime Swarm for Departure
Once the first new queen cell is capped, the focus shifts to physically preparing the old queen and the departing workers for flight. The workers who will leave with the prime swarm undergo significant physiological changes, including a cessation of their normal foraging and brood-tending duties. Instead, these departing bees begin to engorge themselves with stored honey, filling their honey stomachs with enough reserves to last several days.
This mass consumption of honey increases the weight of the departing workers by up to 50%, providing the necessary fuel to travel and secrete wax for building new comb. Concurrently, the workers intentionally reduce the food intake of the old queen, forcing her to slim down. A queen in peak egg-laying condition has an abdomen too large and heavy for sustained flight.
This reduction in her diet causes her abdomen to shrink and her overall body weight to decrease by as much as 25%, making her flight-capable for the journey. Some workers exhibit aggressive behaviors, such as pushing and shaking the queen, forcing her to move continuously across the comb. This constant activity ensures the queen is light enough to fly long distances when the moment of departure arrives.
The Final Signal and Mass Exit
The culmination of the weeks-long preparation is the highly synchronized mass exit of the prime swarm. The final signal that triggers the departure is often acoustic, involving a specific sound known as “piping” produced by the departing queen or workers. This piping signal increases in frequency and intensity, peaking just as the mass exodus begins.
When the signal is received, approximately 40 to 70% of the worker bees stream out of the hive entrance in a chaotic yet coordinated manner, accompanied by the old queen. As they leave, the collective activity within the hive spikes dramatically, involving an increase in “buzz-run” signals and a sudden drop in the density of bees remaining inside the nest. The thousands of bees take to the air, forming a dense, swirling cloud that eventually settles on a temporary location, often a tree branch or fence post, usually within a short distance of the original hive.