Bee Pheromone Communication: The Chemical Language of the Hive

A colony that talks in molecules

A honey bee colony has no central nervous system, yet it behaves like a single coordinated organism. The glue holding tens of thousands of individuals into one coherent unit is chemical: pheromones. These volatile and contact compounds are secreted from specialised exocrine glands and pass from bee to bee through touch, trophallaxis (mouth-to-mouth food sharing) and the shared air of the hive. Unlike a nervous signal that fires and fades in milliseconds, a pheromone can linger for hours or days, building up or dispersing as conditions change, which makes it an ideal medium for regulating slow, colony-wide processes such as reproduction, foraging allocation and defence.

Beekeepers who understand this chemical language gain a genuinely different view of what happens when a hive is opened. A puff of smoke, the removal of a frame, or the loss of a queen are not just physical events to the bees; they are disruptions to an information network, and the colony's subsequent behaviour is best read as a response to altered chemistry rather than simple instinct.

Queen pheromones and colony cohesion

The most studied bee pheromone is queen mandibular pheromone (QMP), a blend of fatty acids and aromatic compounds produced in the queen's mandibular glands. QMP is spread through the retinue of workers that constantly attend her, groom her and pass her scent onward through trophallaxis until, within a short time, a trace of 'queen substance' has reached most of the colony. Its presence signals that a healthy, mated queen is present, which suppresses the workers' ovarian development and their urge to rear a replacement queen.

When a queen dies, is removed, or her pheromone output declines with age, the signal fades unevenly through the colony over a period of hours to a day or two. Workers detect the gap and respond by starting emergency queen cells from young larvae, and in queenless colonies that fail to requeen, some workers' ovaries activate and they begin laying unfertilised (drone) eggs. This is why a rapid pheromone-driven cue, not visual recognition, underlies the colony's near-instant awareness of queenlessness during an inspection.

Queen pheromone also plays a practical role in husbandry. Synthetic queen pheromone lures are used to stabilise nucleus colonies, to calm bees being transported, and to attract swarms into bait hives, since a swarm cluster responds strongly to the scent of established queen substance.

Worker, brood and Nasonov signals

Worker bees produce their own suite of pheromones from glands including the Nasonov gland at the tip of the abdomen, mandibular glands, and tergal glands on the dorsal plates. Nasonov pheromone, a blend dominated by geraniol and citral, is fanned into the air by workers exposing the gland and beating their wings; it acts as a homing beacon, guiding returning foragers, a relocating swarm, or disoriented bees back to the colony entrance or the queen's location. Beekeepers see this behaviour clearly when a hive is moved a short distance or when bees are shaken out in front of a new box: fanning workers quickly orient the rest of the cluster.

Developing brood also emit pheromones, collectively called brood pheromone, which influence adult behaviour in several ways. Brood signals stimulate foraging for pollen (since growing larvae need protein), help regulate the ratio of nurse bees to foragers, and, at high brood pheromone levels, can even suppress ovary development in workers similarly to queen pheromone. This is one reason a strong, actively brooding colony behaves so differently from a broodless one at the same time of year.

Alarm pheromone and defensive behaviour

When a bee stings, or a guard bee perceives a threat, it releases alarm pheromone primarily from the sting apparatus (isopentyl acetate is a major component) and from mandibular glands. This chemical cloud recruits nearby bees to investigate or attack, which is why a single sting during an inspection can rapidly escalate defensiveness if the beekeeper does not use smoke to mask the signal. Smoke works partly by disrupting the bees' ability to detect and respond to alarm pheromone, and partly by triggering a feeding response that occupies the colony's attention.

Guard bees at the entrance also use pheromone cues, alongside recognition of colony-specific cuticular hydrocarbons, to distinguish nestmates from robbers or intruders such as wasps. Understanding that stings compound through pheromone recruitment explains practical advice familiar to every beekeeper: work calmly, avoid crushing bees, and re-smoke promptly after any sting to limit the alarm cascade.

Practical applications for UK beekeepers

Pheromone knowledge translates directly into husbandry decisions. Queen introduction relies on gradual pheromone acceptance, which is why caged queens are released slowly through a candy plug rather than directly onto the comb; workers need time to become accustomed to a new queen's scent before accepting her. Swarm control likewise depends on pheromone dynamics: an ageing queen produces less mandibular pheromone as her physiology declines, and this drop is one of the natural triggers thought to contribute to swarm preparation, alongside congestion and brood-to-bee ratio.

Synthetic pheromone products are commercially available in the UK and elsewhere, including queen pheromone lures for swarm traps and pheromone-based products intended to encourage pollination behaviour on protected crops. While these tools have genuine uses, they work with, rather than replace, sound colony management; a congested, queen-right colony with poor ventilation will still attempt to swarm regardless of any lure placed nearby.