Queen Supersedure: When Colonies Replace Their Queen
The queen is not in charge. This is the first thing to understand about supersedure, and it contradicts the metaphor that the word "queen" creates. She doesn't command. She doesn't decide. She doesn't manage. She lays eggs and produces pheromones. That's her job. The colony's 50,000 workers do everything else - foraging, nursing, building, defending, thermoregulating, navigating, communicating. And when the queen's performance drops below the colony's threshold of tolerance, the workers replace her.
They don't ask permission. They don't file a complaint. They build queen cells.
The Three Types of Queen Cells
Not all queen cells mean the same thing, and the location on the comb tells the story.
Swarm cells appear along the bottom edge of the comb - hanging from the frame's lower bar like peanut-shaped appendages, often 5 to 20 of them. These are the colony's preparation for reproductive swarming. The colony is dividing. Half will leave with the old queen. Half will stay with a new queen raised in these cells. Swarm cells appear in spring and early summer, when the colony is at peak population and the nectar flow is strong. They signal colony health and vigor - the colony is strong enough to reproduce.
Emergency queen cells appear anywhere on the comb face, often in clusters. They're built when the queen dies suddenly or is accidentally killed (crushed during a hive inspection, for instance). The workers can't plan for this - there's no gradual pheromone decline to trigger a controlled replacement. The queen is simply gone. The colony responds by converting existing worker larvae into queens, building queen cells around larvae that are already in worker-sized cells. Emergency cells look rougher, more hastily constructed, and they appear on the flat face of the comb rather than at the edges.
Supersedure cells appear on the face of the comb, typically near the center or upper portion. There are usually only 1 to 3 of them - far fewer than the dozen-plus swarm cells a colony builds. They're well-constructed, deliberately placed, and they appear while the old queen is still alive and still laying. This is the colony making a planned replacement.
The distinction matters for beekeepers, because the management response is different for each. Swarm cells mean the colony wants to divide. Emergency cells mean the queen is already dead. Supersedure cells mean the queen is alive but failing, and the colony has decided to do something about it.
The Trigger
What prompts 50,000 workers to collectively decide their queen isn't good enough?
The answer is chemical. The queen produces queen mandibular pheromone (QMP) - a blend of five primary compounds, including 9-ODA (9-oxo-2-decenoic acid) and 9-HDA (9-hydroxy-2-decenoic acid) - that circulates through the colony via direct contact and secondary transfer among workers. QMP does several things: it inhibits the development of worker ovaries, it attracts workers to attend the queen (the "retinue response"), it signals the queen's presence and quality to the colony, and it suppresses the construction of queen cells.
When QMP production declines, the suppressive effect weakens. Workers begin developing their ovaries slightly. The retinue around the queen thins. And workers begin constructing queen cells - the first visible sign that the colony has evaluated its queen and found her wanting.
QMP production declines for several reasons:
Age. A queen's pheromone output peaks in her first year and declines gradually thereafter. A 3-year-old queen produces measurably less QMP than a 1-year-old queen. This is why commercial beekeeping operations routinely requeen every 1 to 2 years - they replace the queen before the colony does, avoiding the productivity dip that comes with a failing queen and the 2 to 4-week brood gap during natural supersedure.
Poor mating. A queen that mated with too few drones - or whose stored sperm is running low - lays an increasing proportion of unfertilized eggs in worker cells. These eggs develop into drones, which emerge from worker cells as stunted, useless individuals. The workers can detect the pattern: too many drone brood in worker cells signals a poorly mated or sperm-depleted queen. They respond with supersedure.
Injury. A queen whose legs are damaged (from being handled, stepped on by the beekeeper, or injured during a hive inspection) can't move efficiently across the comb to lay eggs. Her laying pattern becomes spotty - scattered empty cells among the brood, instead of the solid, frame-filling pattern of a healthy queen. Workers evaluate laying pattern, and a spotty pattern triggers supersedure.
Disease. A queen infected with Nosema or certain viruses produces fewer eggs and less pheromone. The colony detects both symptoms. Varroa-transmitted viruses like deformed wing virus can affect queen health and pheromone production, and colonies with high Varroa loads supersede more frequently.
The Conversion
When the colony decides to supersede, it selects one to three young worker larvae - typically less than 3 days old - and begins building queen cells around them. The selected larvae are flooded with royal jelly. The quantity of royal jelly a queen larva receives is not just slightly more than a worker larva - it's dramatically more. A queen larva is literally swimming in royal jelly from the moment of selection until the cell is sealed.
The royal jelly triggers a developmental cascade. The larva's genes don't change - queen larvae and worker larvae have identical genomes. What changes is the expression of those genes. Royal jelly contains royalactin, a protein that activates the epidermal growth factor receptor (EGFR) signaling pathway, which in turn activates a cascade of developmental genes that produce queen-specific anatomy: fully developed ovaries, a spermatheca for sperm storage, a longer abdomen, different mandible shape, the pheromone glands that produce QMP, and a body plan optimized for a lifespan of 3 to 5 years rather than 6 weeks.
The same genome. Different food. Different organism. The epigenetic switch between worker and queen is one of the most dramatic examples of nutritional caste determination in the animal kingdom.
The queen cell is sealed on day 8 after the egg was laid. The queen pupa develops inside the cell for roughly another 8 days. A new queen emerges on approximately day 16 from egg-laying - about 5 days earlier than a worker bee's 21-day development period. The shorter development time is another queen-specific trait: faster development means less time vulnerable in the cell, and in competition scenarios (swarming), the first queen to emerge has a significant advantage.
The Mother-Daughter Question
Here's where supersedure gets strange, at least by human standards.
In swarming, the outcome is clear: the old queen leaves with the swarm, the new queen inherits the original hive. The two queens never coexist in the same colony. In emergency replacement, the old queen is already dead.
In supersedure, the old queen is alive when her replacement emerges. What happens next varies, and nobody fully understands why.
Scenario one: the old queen is killed. The new queen emerges, finds the old queen, and stings her to death. Or the workers ball the old queen - surrounding her in a tight cluster that overheats and suffocates her. The colony transitions to the new queen cleanly. This is the most commonly assumed outcome.
Scenario two: coexistence. The new queen emerges, and both queens coexist in the hive for days, weeks, or occasionally months. Both may lay eggs simultaneously. The workers attend both queens. The colony functions with two laying queens on the same comb.
Beekeepers discover this occasionally and are invariably surprised. They open the hive, pull a frame, and see two queens - usually distinguishable by size (the old queen is often larger and more worn) and behavior (the old queen moves more slowly). The colony isn't confused. It's running both queens in parallel, perhaps using the overlap to ensure that the new queen is successfully mated and laying well before the old queen is retired.
The coexistence period eventually ends. The old queen either dies naturally, is killed by the new queen, or is killed by workers. But the fact that colonies tolerate dual queens during supersedure - when they would never tolerate it during swarming - suggests that the colony "knows" this is a replacement, not a split, and manages the transition accordingly.
Scenario three: supersedure failure. The new queen emerges but fails to mate successfully (bad weather during the mating period, insufficient drones at the DCA, predation during the mating flight). The colony now has a failed replacement queen and an aging original queen. If the original queen is still laying, the colony may kill the failed replacement and try again. If the original queen has stopped laying entirely, the colony is in trouble - it may become hopelessly queenless, with no larvae young enough to raise another queen.
The Emergency Version
When a queen dies suddenly - crushed during inspection, killed by a predator, or lost during a mating flight - the colony's response is faster and less elegant than supersedure.
The loss of QMP is detected within hours. Workers begin checking larvae across the brood nest, selecting candidates young enough to be converted. The critical window: a worker larva must be less than approximately 3 days old (from hatching, not from egg-laying) to be successfully converted to a queen. Older larvae have already been fed the worker diet for too long, and the developmental switch can't fully activate. Queens raised from larvae older than 3 days may emerge with partially developed ovaries, reduced pheromone output, and shorter lifespans - "emergency queens" that are functional but suboptimal.
The colony hedges its bets by building multiple emergency cells - sometimes 10 to 20 or more. The first queen to emerge typically destroys the other queen cells by chewing through the sides and stinging the pupae inside. If two queens emerge simultaneously, they fight. The winner inherits the colony.
The emergency response introduces a brood gap. The last eggs the dead queen laid take 21 days to emerge as workers. No new eggs are laid until the emergency queen emerges (day 16), mates (roughly day 20 to 25 from the original queen's death), and begins laying (day 23 to 30). The first worker brood from the new queen doesn't emerge until day 44 to 51 after the original queen's death. During this 6 to 7-week gap, no new workers are being produced. The colony's population declines by roughly 1,000 to 2,000 bees per day (the normal attrition rate of forager deaths).
A colony that loses its queen in late summer - August or September - may not have enough time to raise a new queen, have her mate, rebuild the population, and store enough honey before winter. This is one of the reasons late-summer colony losses are so devastating: a queen failure in August, if not detected and corrected by the beekeeper, is often a death sentence for the colony.
The Laying Worker Problem
If a colony fails to raise a replacement queen - because no larvae were young enough to convert, because all emergency queens failed to mate, or because the beekeeper didn't intervene - the colony becomes hopelessly queenless. Without QMP, the suppression of worker ovary development lifts. Within 2 to 3 weeks, some workers develop functional ovaries and begin laying eggs.
Worker-laid eggs are always unfertilized, because workers never mate. Unfertilized eggs develop into drones. So a laying-worker colony produces only drones - no new workers. The population spirals downward as existing workers age and die without replacement. The drones produced are often stunted (raised in worker-sized cells) and rarely contribute to mating populations.
A laying-worker colony is almost impossible to requeen by simply introducing a new queen. The laying workers produce enough pseudo-QMP to make the colony believe it has a queen. A caged queen introduced to a laying-worker colony is often killed by the workers, who perceive her not as a savior but as a rival.
The traditional remedy is to combine the laying-worker colony with a strong, queenright colony using the newspaper method - stacking the queenless colony on top of the queenright colony with a sheet of newspaper between them. The bees chew through the newspaper over 24 to 48 hours, during which the pheromones mix. The queenright colony's QMP suppresses the laying workers. The combined colony accepts the queen. The laying workers revert to normal worker behavior.
The Genetics of Replacement
There's an underappreciated genetic consequence to supersedure. When a colony supersedes, the replacement queen mates with a new set of drones at the DCA. The colony's genetic composition changes dramatically in one generation.
The old queen's workers were fathered by the drones she mated with 1, 2, or 3 years ago - drones from colonies that existed in the area at that time. The new queen's workers will be fathered by drones from colonies that exist now. The patrilines shift entirely. The colony's disease resistance profile changes. Its behavioral tendencies change. Its temperament may change.
Beekeepers sometimes report that a colony's personality shifts after supersedure - a gentle colony becomes defensive, or a defensive colony becomes gentle. This isn't the colony "learning" new behavior. It's the colony's genetic composition changing as the old queen's offspring age out and the new queen's offspring take over. The full genetic turnover takes roughly 6 to 8 weeks after the new queen begins laying - the time required for the last of the old queen's workers to die and be replaced by the new queen's daughters.
For breeding programs, uncontrolled supersedure is a problem. A breeder who selected a queen for Varroa resistance, gentleness, or productivity loses that genetic investment when the colony supersedes and the replacement queen mates with unselected drones at the local DCA. The genetics revert to whatever the local drone population provides. This is one of the reasons queen breeders mark their queens with a dot of paint - so they can detect supersedure (the marked queen is gone, replaced by an unmarked daughter) and decide whether to accept the replacement or introduce a new selected queen.
The Silent Revolution
Supersedure is one of the most common events in a beehive and one of the least observed. It happens quietly. The colony builds a few cells. A queen emerges. The old queen disappears. The colony continues. Many beekeepers never see it happen. They open the hive one week and everything looks normal. They open it three weeks later and the queen is different - younger, smaller, unmarked - and the only evidence is an empty queen cell or two on the comb face.
The colony's decision-making process is distributed, chemical, and invisible. No single worker decided to supersede. The aggregate pheromone level dropped below a threshold. Workers who happened to be near young larvae began building queen cells. Other workers fed the selected larvae royal jelly. The process emerged from thousands of individual responses to chemical signals, with no coordinator, no vote, and no debate.
It's a coup carried out by chemical consensus. The workers don't overthrow their queen with violence (usually). They simply start building her replacement, and the pheromone math does the rest. The old queen doesn't resist - she can't. She doesn't even know it's happening, as far as anyone can determine. She continues laying eggs while, a few cells away, her successor is growing in a peanut-shaped wax chamber flooded with royal jelly.
Fifty thousand workers. One failing queen. One to three queen cells. A 12-minute mating flight. A new genetic future. The colony didn't ask anyone's opinion. It read the pheromone data, found the numbers wanting, and made a change. The decision was unanimous because it wasn't a decision. It was chemistry.