One of the most regular issues that beekeepers will be facing is the loss (or the perceived loss) of a queen.
Now Queen Bees are incredibly hard to find, and you can safely assume, that whenever you really want to find the queen, you simply won’t. So, the usual “sign” that beekeepers use to determine that there must be no queen is that there are no eggs, or even no brood.
However, it only works the other way around. Eggs are a nearly sure sign that there was a queen around this frame within the past 3 days, as it takes 3 days for an egg to hatch into a young larva. Capped (worker) brood is a sign that there was a queen up to at least 21 days ago.
Even to this “sure” sign there is an exception, and that is laying workers. Eventually when a hive is without a queen, and subsequently without brood up to 30% of a colony’s workers will gradually start laying their own eggs. Of course, these eggs are not fertilized, as the laying workers never got mated, so all the larvae that hatch out of these eggs will be drones. This is an emergency last ditch effort of the hive to spread its genes as it is doomed to die. During the course of the evolution of the honeybee, beekeepers only played a role in the last 100 years, thus biologically the sudden introduction of a queen is generally not a thing that laying workers would anticipate. Thus, these laying workers will generally be hostile to any introduced queen, which is why hives with laying workers generally can’t be requeened easily. Of course, there always are exceptions to the rule.
How queens are made
When dealing with the loss and raising of a new queen one has to keep 3 numbers in ones mind: 3, 5 and 8. The development of a young queen begins as an egg. It takes 3 days for an egg to hatch. The next 5 days the queen will spend as a larva, eating gelee royale (the feeding of gelee royale is the only reason an egg will turn into a queen, and not a worker bee). After this, the worker bees will cap the cell and the queen larva will transform into a queen for the next 8 days. This means that from laying an egg to queen it takes 16 days until the new queen hatches.
However, there is one exception: when dealing with emergency cells the bees do not rear a queen from an egg, but from a young 1-day-old larva. It has been proven that until 36 hours after hatching the development of worker bees and queens is the same. This is also why grafted queens are raised from 1-day old larvae. So in the case of an emergency (or grafted) cell it only takes 12 days for a new queen to hatch, 4 days as a larva, and 8 days as a pupa in a capped cell. After hatching a young queen will generally fly out to be mated and start laying eggs within 2 weeks. But bad weather can delay this for about 1 or 2 weeks. Understanding these timeframes is important for assessing the situation, so keep those in mind.
The loss of a queen
There are 3 ways for a colony to lose its queen:
Swarming
First, she might simply swarm off, in that case the hive has raised multiple so called swarm cells before the old queen swarmed off. Some of the virgin queens might also leave with secondary swarms, but generally one virgin queen should stay behind, and fly out to get mated. If she returns, she usually should start laying within 2 weeks of her hatching. If she does not return, the hive will not have any eggs or larvae left (as the old queen left the hive around 1-2 weeks ago) and the hive will eventually develop laying workers.
Queen gets replaced
Secondly the bees might decide that the queen is no longer fertile enough, this usually happens with older queens, or ones that were poorly mated. It is a result of the queen laying fewer eggs, and thus producing less queen pheromone. The hive will raise so called supersedure cells, from the eggs that the queen is still able to lay. These cells will look remarkably like swarm cells, but it will generally be only 1 or 2. Supersedure also tends to happen later in summer, after the main swarming season. Often (but not always) the old queen will continue to lay eggs, while the new queen hatches and eventually gets mated. And both queens might be laying eggs in the hive at the same time for a few weeks, before the older one gets “retired”. However, supersedure not always works this way, sometimes the old queen is removed before the new queen starts laying. And if the mating flight of the supersedure queen is unsuccessful, the hive will also end up queen less and without the means to raise a new queen. This is why beekeepers are generally advised to replace their queens early.
Queen dies suddenly
The third way involves the queen suddenly dying, this could be due to disease or old age, but usually involves the beekeeper simply squishing her due to carelessness. In this case there will still be eggs and young larvae in the hive, but only in worker cells, as the bees did not have the chance to erect other cells beforehand. The worker bees will realize that the queen is gone as they can no longer smell her pheromone. Over the course of the next day or two they will start to raise so called emergency cells. What this means is that they will start feeding 1 day old larvae in random worker cells like they were in queen cells. They will also start to extend the tip of these worker cells downwards to make them look more similar to queen cells. Due to this this emergency cells tend to have a “kink” in them and will usually be found all across the middle of the brood nest where there were young larvae when the “accident” happened. A stronger hive will usually raise multiple/many emergency cells, but these cells tend to not result in swarming, and the first virgin queen that hatches will take care of her sisters. As before, within 2 weeks after hatching the queen should be mated and laying. If she gets lost on her mating flight, again the hive will not have any means to raise another queen and would eventually develop laying workers.
To make things more messy combinations of these 3 cases can occur, for example a hive could lose its queen at the height of swarming season and then decide that they do not just want to raise an emergency queen, but that they are also strong enough to swarm.
Apart from visually spotting a queen (or even more rarely a virgin queen, which usually will look like a queen, just with a smaller abdomen and walking around much more nimbly), the presence of eggs, queen cells and with enough experience the behavior of the bees will be the signs that tell the beekeeper what is happening.
What to do when a hive is without queen?
Let us now assume that you have a hive that you think is queen less. What do you do?
Make sure the hive is really queenless
Well obviously first of all look for signs of the queen, as we assume that you will not find the queen anyways (Maybe you will, I certainly will not if I have to). Signs means eggs and brood. There might already be a new queen, but she might just have started laying on one frame, or she might not be laying at all yet.
The amount of brood and the stages that you find will give you an indication of where the hive is at with regards to the timeline. Obviously, eggs mean “queen is likely still here”, while no eggs but larvae mean “queen was still here a few days ago”. Only capped brood means that no eggs have been laid in at least the last 9 days, and if there is no (worker) brood at all you can safely assume that no queen has been laying for at least 21 days.
Check for queen cells
Next you should look for signs of queen cells, those could be cells that have been freshly raised, capped queen cells or even ones that have already hatched (or opened on the side). By the way capped queen cells are very delicate, after they have been capped up until a day or 2 before they hatch.
Ideally the state of brood you will find will correlate to the state of queen cells that are in there. Meaning that if you find only open emergency cells and open brood but no eggs the queen disappeared a few days ago. Capped queen cells but young brood (and maybe even a few eggs) is an indication that you are looking at a supersedure or swarming as those cells must have been raised before the queen stopped laying. If there are queen cells that are open (hatched) and either no brood at all, or only capped brood things obviously must have already progressed a bit further and it is likely that there is a virgin queen in the hive.
After you have determined what state your hive is at, you will now have to figure out what to do. Generally speaking, doing nothing and coming back 1 or 2 weeks later is often a very good option. Requeening, i.e., inserting your own mated or virgin queen will only work reliably if there are no queens or active (with a living larva inside) queen cells left.
If your hive has all capped brood, and no queen cells have yet hatched (i.e., they are all still capped) you can destroy all queen cells. This will ensure that the bees have no means left to raise their own queen, in such a state they will be much more likely to accept an introduced queen. If you are breaking queen cells you have to be absolutely sure you do not miss a cell that can be hidden somewhere. Shake the bees off all brood frames (similar to an AFB inspection or swarm control) and thoroughly search for queen cells.
As soon as you find at least one queen cell that has hatched you have to assume there is a virgin queen inside. Remember that virgin queens are essentially impossible to find. I jokingly always say that they have a cloaking device and can teleport themselves (well no but they have wings). Do NOT attempt to introduce a queen to such a hive with a virgin queen in it, it is pointless. She will just be killed.
The state of the capped brood will tell you what to do instead. If there is still plenty of capped worker brood you can assume that the young queen has only recently hatched. In such an instance, and if the weather is still warm, I would simply leave the hive alone and check back around 2 weeks later. Everything going well she should then be mated, and you will see the first eggs and maybe young larvae.
Queens can get lost during their mating flight
If you find one (or many) hatched queen cells but there is no brood left, there is a chance that the queen got lost during her mating flight. If that’s the case the bees will be more agitated, and you will see many bees fanning with their wings. Note that as things progress and laying workers are starting to take over this fanning behavior might no longer appear. Also, sometimes this fanning behavior can happen when a queen has just recently started laying, but her pheromone production is not yet as strong. So, it is not a sure sign.
Example of fanning bees
But is there a sure sign to tell if a hive has a queen/virgin or not? Luckily for us there is.
The creation of emergency cells out of young worker brood will only happen if there is neither a mated nor a virgin queen. With this in mind you can use a small trick to figure out whether a hive has a queen or not. Simply insert a frame with eggs and open brood into the hive you are unsure about. Technically the bees will require 1-day old larvae, but if you have eggs and brood on a frame its likely to have a few cells with just the right age of larva in them, the bees will figure it out.
Wait a few days to a week (technically you have 12 days before a virgin queen would be able to hatch) and check for emergency cells. If they do not raise any cells within a few days the bees obviously think that there is no need to raise a new queen. Usually because there already is one in there or because there are laying workers. Introducing another queen into such a hive is doomed to fail.
If you find emergency cells on the frame obviously the bees think that they have no queen (and they will know) you can now let the bees proceed with raising their queen, or decide to introduce another queen. If you want to do so you have to break all queen cells (do not miss any!) before introducing the new queen with her cage.
So, whenever you are faced with a hive that is presumably queen less make sure to find out as much as you can about what happened and in what state the hive actually is. Make sure that the hive really is queen less before buying and introducing another queen, as you might doom her to die otherwise.