The life span of a honey bee depends on many variables. The three castes, or categories, of honey bees have different life spans. Queens can live for three to five years; workers for a few weeks; and drones, which are the only males, live only until they mate with the queen, after which they die. The stages of life for bees are larva, pupa and adult.
Each bee's life begins as an egg developing in the queen. She has an organ called a spermatheca that contains sperm from her previous mating. According to entomologist Gordon D. Waller of the Carl Hayden Center for Bee Research, the queen's body controls the release of sperm and therefore whether or not the egg is fertilized. Fertilized eggs will become females, and unfertilized eggs will become males. The queen lays each egg in an empty honeycomb cell, where it continues to develop into the larval stage, then hatches.
Young nurse bee workers produce a food called royal jelly, which they feed to the larvae and the queen. For the first day, every larva receives a large amount of jelly. Then, older worker bee larvae receive a reduced diet containing pollen and honey. If the larva is kept on the heavy diet of royal jelly, it will develop into a queen. Drone larvae are larger, and are fed a diet heavier in pollen. The larvae molt several times as they progress through stages called instars. Queens emerge in 16 days, workers in 21 days and drones in 24 days.
Drones live the shortest lives of the three castes of honey bees. They can't perform tasks other than mating with the queen, so the hive only raises them when warm weather allows mating. They die after mating. Remaining drones are driven out of the hive for the winter.
Worker bees begin their lives as "house bees," performing many tasks in the hive for the first three weeks of their lives. The Food and Agricultural Organization of the United Nations describes how, at mid-life, their glands for producing royal jelly and beeswax have weakened. They make some short flights to orient themselves around the area of the hive, before becoming "field bees" that forage for nectar and pollen for another three weeks.
Queens can live for three to five years. Queens do not need to continuously mate, as they can carry the sperm in their bodies for the rest of their lives. Long before they are old enough to mate, when they first emerge from the egg as larvae, they will seek any rival queens and fight with them to the death in their pupal cells. In prosperous times, the worker bees produce more royal jelly than the worker larvae can consume, so they begin to raise new queens. Then the old queen leaves the hive to start another, followed by half of the hive population in a swarm. Sometimes the old queen will remain after laying all of her fertilized eggs; known as a "drone layer", she lays only eggs that will become drones. Her daughter, the new queen, can live together with the old queen, so that, contrary to popular wisdom, sometimes a honeybee hive can have two queens.
An article published in the Public Library of Science describes the double threat posed by the parasitic phorid fly Apocephalus borealis, not to be confused with the fire-ant decapitating phorid fly Pseudacteon. A. borealis causes bees to leave the hive and die before the fly's larvae emerge from the dead bees. The fly also brings deformed wing virus. Other threats to honey bee populations include pesticides, habitat loss and mites. Overuse of pesticides can kill bees in the field, and systemic insecticides applied to seeds can contaminate pollen taken back to feed the hive. Loss of diversity and continuity in the habitat add more challenges. The United States Department of Agriculture describes colony collapse disorder as a mysterious syndrome in which the workers of a hive disappear, leaving only the queen and immature bees. Its cause is not yet fully understood.
