Colonies have a single queen. And when they don't, they are queenless. This state is called queenlessness. There's nothing complicated about the definition of queenlessness!
But when it occurs, it is an imminent threat to the future of the colony.
The existence of a colony depends on constant growth and the renewal of resources. Given the short life cycle of the worker bee, maintaining the status quo requires a productive queen, laying efficiently to replace dying workers. In fact, a healthy colony grows at a tremendous rate and the emergence of new bees outstrips the loss of aging bees. The queen's 2,000 per day egg-laying productivity is crucial.
When the queen is lost everything changes and this article looks at the causes and how the beekeeper can react.
There are a wide number of reasons a colony can lose its queen.
The queen is central to the colony but also as vulnerable to disease and pests as any other bee. She will have help, in the form of attendant worker bees, but there is never an absolute assurance she will survive all threats.
This is a real risk when inspections take place. Extra precautions should be taken when handling frames, to lower the risk of killing the queen. For example, when examining a frame that may include the queen - and you will never know for sure unless you spot her - hold the frame over the box, so that if the queen falls from the frame she falls into the box below.
The colony has an innate sense of how productive the queen is at all times, through the spread and detection of pheromones. If the colony believes the queen is under-performing they may kill her.
The mating flights the queen makes early in her life are treacherous. There are many ways in which she may die and not return to the colony.
One queen killing another might seem like it will always leave a victor, hence leaving the colony with a queen. But it is also possible that two queens can fight to the death, with both dying.
One surefire way to know your hive is not queenless is obviously to spot her! There are various ways to do this, directly.
If you are purchasing a package of bees, it is simple to pay a small amount (often $5) to have the queen marked. This places a small dot of paint on her thorax which makes her easier to spot during inspections. A different color paint is used each year so that the age of the queen is easy to determine in subsequent years.
The eagle-eyed beekeeper will locate the queen in various ways as each frame is scanned. One will be the way workers line up as they are attending her.
As the colony grows over the summer, more boxes will be added. In a Langstroth, brood will be in the lower boxes, with honey being stored in upper boxes. This means the queen will generally be in the lower boxes of the colony. Note however, that nothing is guaranteed.
If a queen excluder is used, this limits the boxes in which she might be found. However, PerfectBee does not recommend the use of a queen excluder in the year a colony is established, when it is essential that the bees can continue their work unimpeded in the hope they can build sufficient reserves to survive the winter.
If you have determined your hive is queenless, it's important to get a sense of how long this has been the case. The progress of brood from eggs to uncapped brood to capped brood and finally to adult bees offer the clues you need.
Finding eggs (assuming they are not from laying workers - see below) shows that the queen was there within the last 3 days. That also means that there is a reasonably extended "pipeline" of bees on their way, to emerge as adults. Since you want to avoid a significant gap in the emergence of adult bees (to offset adult bees that die), the presence of eggs mean you have time - but not much - in which to fix the situation.
Your hive inspections should usually include an effort to find eggs, to bring at least some peace of mind. An absence of eggs is a warning sign you should investigate.
Another important sign of queenlessness is the appearance of laying workers. However, by this stage it's late in the game, since they don't become evident until 2-4 weeks after the queen was lost.
As workers, they will not have mated, so their only option is to lay unfertilized eggs. This results in drones. This production of only drones becomes a huge problem for the colony, since there are no workers to carry out the roles they fulfill, like foraging. The colony will soon die.
The following signs are clues of laying workers.
It is thought that colonies have a small number of laying workers, even when a queen exists, but in such tiny numbers they create no problems. Here's a neat video of a laying worker "caught in the act".
There are two main ways to respond to queenlessness - let nature take its course and allow the bees to create another queen or introduce a mated queen.
Bees will often take the situation into their own hands when a queen is lost and create a new queen. The problem is that it takes time. Raising a queen from an egg takes 15 days. Then she will need to mate, which may take another five days or so (including the risk associated with her mating flights).
If you have gone 3 weeks without brood, depending on how long it took for the colony to create a new queen, that may be too long for the colony to survive.
Another problem with this scenario is that the colony has a small window of opportunity. To raise a new queen, the colony needs two things - a fertilized egg and the ability to feed a larva royal jelly beyond its third day.
The fertilized egg must come from the (now departed) queen - so that starts the clock. If she lays an egg on her last day, the colony must identify the issue and elect to raise a queen before one of the larva is three days old. If they realize after that time, then they will have missed the opportunity for "continuous royal jelly" for a selected larva and no queen can be produced.
Given the time to create a new queen, a common alternative is for the beekeeper to introduce a mated queen. These can be purchased in a queen cage, often with one or two workers with her. There is a significant risk of rejection by the colony. It is therefore important the queen is introduced in a cage, with a piece of candy at one end providing a "timer", of sorts. This is like the process many beekeepers use when establishing a colony from a package of bees.
When introducing the queen, carefully watch the reception she receives. If workers "attack" the cage and cannot be easily brushed off then the chances are they would not accept her. In such a situation, remove her for a day or two then try again.
Often, though, the colony is eager to receive a new queen and will accept her. When she is freed from her cage after a couple of days, she will become familiar with her new surroundings and then start laying.
Introduction of a mated queen can get you back to a queenright situation in about a week or less. If you caught queenlessness early enough, you stand a good chance of recovery to a healthy beehive.