Bee castes
A honeybee colony is a single family: one mother queen and thousands of her offspring, mostly workers, plus drones at certain times of year. These groups are often referred to as castes. When working with bees and inspecting colonies its important to understand each caste, the role it plays in the colony, and what determines the caste of an individual bee.
Queen
Starting with the most important the queen. She has the only role fulfilled by a singular bee in the entire colony. A colony with the proper conditions can often replace a failing or lost queen on their own. However, when that fails a colony without a queen is doomed to die out.
Who she is — The one egg-laying female per colony who is the source of all successful reproduction.
What she does — Lays eggs (fertilized for workers, unfertilized for drones) and releases pheromones that help the colony behave as a unit.
Where she comes from — Fertilized egg laid by a queen which is fed royal jelly while it is a larva. Only the bees, not the keeper, can raise a new queen by producing and feeding royal jelly. There are multiple conditions in which they may choose to do this (swarm, supersedure, or emergency). A beekeeper trying to raise new queens can often simulate situations that trigger swarm or emergency behavior from the bees (see Queen development timeline). A new virgin queen after emerging goes on mating flights, and stores enough sperm to fertilize eggs for her lifespan. Then she begins laying, and except for swarming will not leave the hive again.
Workers
Who they are — Female bees hatched from fertilized eggs. They inherit DNA from both the queen and the drones she mated with.
What they do — Almost all the work: nursing larvae, cleaning, building wax, guarding, foraging for nectar and pollen, and regulating temperature. A summer worker might live roughly 4–6 weeks; winter bees can live many months.
Where they come from — The queen lays fertilized eggs in worker-sized cells. Larvae get royal jelly briefly, then a mix of jelly, nectar, and pollen until the cell is capped. About 21 days after the egg was laid, an adult worker emerges.
Drones
Who they are — Male bees hatched from unfertilized eggs (they have a mother but no father; they carry only the queen’s genes).
What they do — Their main role is mating with virgin queens from other colonies. They do not forage, sting, or build wax. In many regions drones are expelled in fall when colonies look to conserve resources for winter.
Where they come from — The queen (or sometimes workers in a laying-worker situation) lays unfertilized eggs in larger drone cells. Development from egg to adult is roughly 24 days.
Takeaway: one colony, one breeding female at a time, thousands of sisters doing the work, and males whose job is mostly genetic exchange between colonies.