In a bee hive, there’s usually just one queen. What happens when the queen dies? How do the bees replace her?

When a bee colony loses a queen – say, she’s accidentally killed – the worker bees notice the absence of a chemical she produces – a pheromone. Pheromones are chemicals that serve as a stimulus to other individuals of the same species for one or more behavioral responses. In the case of bees, in response to the absence of the queen’s scent, the workers begin a process of emergency queen rearing. They start building queen-size rearing chambers for about 10 to 20 young female larvae.

The process of royal succession is similar if the queen is dying of old age. As she ages, the queen produces fewer pheromones. The decline in pheromone concentration signals the workers to start building queen-size cells in the hive. If the queen is still alive, she herself lays the eggs of her potential successors into these cells.

Ordinarily, these eggs would hatch into female larvae who would grow up as workers. But since they’re inside special larger, vertically-oriented cells, the workers know to feed these potential queens a special food called royal jelly. This diet creates a fertile queen rather than a sterile worker. So, for example, all of the developing queens have the fully developed ovaries needed to lay eggs.

The first potential queen bee to emerge from her cell as an adult will sting the other developing queens to death in their cells before they hatch. If two should emerge at the same time, then the rival queens will have a battle to the death.

Bottom line: Potential queens are fed a special food called “royal jelly.” Ultimately, developing queens in a single hive might fight to the death to determine which one will become queen.