Significance
The queen bee in any hive is the only bee with fully developed ovaries and is therefore the only bee that can repopulate the hive. Without a queen, the bee colony would die out.
Function
The life of a new queen begins once an old queen bee has laid special vertical eggs in larger-than-normal cells called queen cups. This happens when the hive gets too crowded. Some of the bees need to form a swarm to leave and start a new hive. There will be more than one queen egg. When the eggs hatch, the baby queens fight until just one is left alive. This survivor then functions as queen of the new hive.
Royal Jelly
Another bee in a hive is the nurser bee. This bee produces a mix of chemicals, digested pollen and honey. She secretes it from a gland in the head to feed the young queen bee larvae. Royal jelly is fed to future queens to make them larger. Ordinary bee larvae are not fed royal jelly.
Reproduction
A queen bee will mate with around a dozen drone bees in one short period of time on one day. This is accomplished by flying to what is called the drone congregation area. Once she has finished mating, the sperm is stored in her spematheca, an organ only the queen has. She will return to the hive and lay approximately 1,000 eggs in her two to five year lifespan.
Marking
Beekeepers of managed hives mark their queen bees with a dot of colored paint on the queen's thorax. The dots will be of different colors on different queens depending on a color chart which provides a color for specific years.