A Honey Bee colony swarming is a natural process, it is how the Bee colony reproduces itself. When a colony swarms, it splits into two distinct colonies, one which remains in the Hive whereas the other leaves to find a new place to nest. It is the original Queen that leaves the Hive with roughly half of the Worker Bees and a ~3 day supply of Honey.
After leaving the Hive, the original Queen finds somewhere nearby to rest, and the Workers join her to form the distinctive swarm cluster.
The swarm will stay here until scout bees decide on a location for their new home. As this process could take from several hours up to a day, Beekeepers can be called to collect the Swarm, especially if it is in a location where it poses a hazard.
The images below show some of the locations Swarms can end up resting:-
When swarming Bees are not usually aggressive, as they are laden with Honey and have no Brood to protect, however if the Swarm and Queen are threatened, the of course the Bees will attempt to defend themselves.
If you are someone you know comes across a Swarm of Bees, the best course of action is to keep your distance and contact your local Beekeeping Association, who will come and collect it.
The video below gives an explanation as to why Bees swarm:-
Signs of Swarm Preparations
To a non-beekeeper, a Swarm can appear as if it formed with no warning, with huge amounts of Bees "suddenly" deciding to leave the Hive and move elsewhere, but this really isn't the case. In the days and weeks before, there are signs within the Hive that can be used to warn that the Bees are considering swarming.
In Scotland, Swarming usually occurs between late April and Early August, but it depends on the weather conditions, a mild Winter and Warm Spring will bring the date forward for example.
Sign 1 : Drone Brood
When colonies have sufficiently strengthened themselves after Winter, they can start to use resources to complete non-survival critical jobs like raising Drones. Drones are a vital part of the colony's development, and doesn't always mean the colony is trying to Swarm, but without Drones the colony won't Swarm, so this is the first warning sign.
The image below shows the difference between the flat worker brood and the domed drone brood:-
Sign 2 : Queen Cups
The second sign that a colony is preparing to swarm is the production of Queen Cups. These are the foundation of the cells that the eggs for new Queens will be lain in. Due to the large size of the Queen, the Queen Cells are too large to fit into the comb, and stick out like acorn cups, hanging down from the comb. The following image shows two Queen cups, surrounded by open Honey stores:-
The existence of Queen cups doesn't always mean swarming preparations are underway either, sometimes the workers make practice cups known as "play cups". It is only once the Queen has lain eggs within the Queen Cups that the Swarming preparations have begun.
Any Queen Cups should be carefully monitored to make sure the Beekeeper knows when eggs have been lain within them.
Sign 3 : Queen Cells
Once an egg has been lain within a Queen Cup, it becomes a Queen Cell. As the new Queen develops within the Queen Cell, the Workers enlarge the Cell until it hangs down from the comb, as can be seen in the image below:-
It is vital that the Beekeeper has a good understanding of the life cycle of the Queen as it is when the Queen Cells are sealed that the colony will begin to Swarm.
This means that, as the Queen Cells are sealed on day 8 after being laid, a Beekeeper has just a week to prepare Swarm Control Measures.
Once a Swarm has left with the original Queen, the remaining colony will wait until the new Queen/s hatch (day 16 after being laid). The first Queen to hatch will normally kill all the other Queens still trapped inside their cells and become the colony's new ruler.
Queen Bees have long life span compared to other Bees within the colony, living sometimes for up to 4-5 years, however they will eventually die. When this occurs, or usually as an older Queen being to fail, the Workers can rear a replacement Queen from previously laid worker larvae. This replacement of the old Queen will happen without Swarming and is known as Supersedure. This usually happens later in the year than Swarming, around early September (but again is weather dependant).
Supersedure cells look different from Swarm cells as they are usually larger and found not at the bottom of the comb, but usually within the worker brood in the middle of frames.
After hatching, the Virgin Queen will the go on a mating flight and return, taking control of the colony. She will usually kill the original Queen, but sometimes the colony will support two laying Queens for several weeks without issues.
By spotting the signs above, it is possible to get some notice that Swarming may be about to occur. Whilst swarming is a natural process of a colony, it is a problem for Beekeepers as if it happens, they will lose about half of their Bees, reducing the Hive's Honey output that year (alongside the problems of swarms in neighbours gardens!).
The "Nucleus" Method
The Nucleus Method of Swarm control allows a Beekeeper to artificially create the conditions of a Swarm but in a way they (mostly!) control. This method will also provide a "backup" Queen if things go wrong in one part of the split colony.
In order to use this method, additional equipment is required:-
A spare Hive Stand.
A Nucleus (or Nuc) Hive.
Sugar syrup & Feeder
Spare frames of drawn comb (if possible) or with foundation.
A Nucleus Hive if very different from a full Hive. It consists of only one brood box, containing only six frames. It is simply designed to hold the Queen (the nucleus of a colony, hence the name), some brood and a small number of Workers.
The image below shows a polystyrene nucleus hive:-
Stage 1 :
Place Nuc next to main Hive and remove all its frames. Open main Hive and locate the Queen.
Stage 2 :
Place the frame containing the Queen carefully into the middle of the Nuc box. Destroy any Queen Cells on this frame. Then place two frames that contain a good amount of food and place them on either side of the Queen's frame, then slide all three to one end of the Nuc box.
Stage 3 :
Transfer two frames of Bees into the Nuc by shaking them into it. This will transfer Workers that acting as nurse bees as well as others that are foragers.
Stage 4 :
Fill the gaps in the Nuc with the spare frames of drawn Comb. Then close up the Nuc, blocking the entrance with a plug of grass to keep the Bees temporarily contained within it. Move the Nuc to a different location within the Apiary.
Stage 5 :
Check the remaining frames in the main Hive, destroying any sealed Queens Cells. Destroy all other Queen Cells but one. This Cell containing a Larva will become the new Queen for this colony so it is good practice to mark that frame with a pin for ease of finding.
Stage 6 :
Push remaining frames together so that the Brood is again in one location, then fill the remaining spaces with spare frames, then replace all other sections of the Hive. If the grass hasn't withered enough to allow the Bees to leave the Nuc by the next evening, remove it also.
Any foraging Worker Bees will most likely return to the original Hive, leaving only the Nurse Worker Bees with the Queen in the Nuc.
Once these come of age, they will usually stay with the Nuc.
What happens next
After the colony is split using the method above, the original Hive has no Queen, and so cannot swarm. The Nuc colony will also not swarm as it has no flying workers (after an initial exodus) and no Queen Cells.
The original Hive should be checked after four days then again four days later, with any other developing Queen Cells again destroyed. Care must be taken not to damage the new chosen Queen, obviously.
After this, the New Queen should hatch, go on her mating flight and become the Hive's new ruler. This Hive will not swarm at this point as the destruction of all other Queen Cells means the colony cannot leave behind a developing Queen, so they will not go.
If this new Queen is lost, or fails to mate, then the main Hive can be re-Queened from the Nuc.
If the Nuc is not required to re-Queen the original Hive, then the Nuc can be used as a starter colony and moved into a new full Hive.
Finally, the Nuc and original Hive colonies could be reunited if the old Queen is to be replaced.
As stated earlier, if you are unlucky enough to lose a swarm, they generally don't go far. If they can be found, they can be recaptured.
Finding the Bees is sometimes the easy part, depending on where they gather. a low hanging tree branch would be ideal from the point of view of a Beekeeper trying to collect them, but not always the Bees first choice.
The Bees are looking for a safe place to wait for several hours without being disturbed, so this usually means high up away from big mammals (including us!). It is common to find swarms in the upper branches of trees, on roofs or even on top of traffic lights. If they are in difficult to access locations, it may be too unsafe to attempt a capture.
The key aim of Swarm Capture is to capture the Queen, as wherever she goes, the rest of the swarm will follow. So if the Queen is placed in a container such as large box, the swarm will follow, gathering around her.
Kit Needed to capture a swarm:-
Bee suit or veil
Smoker + fuel
Large cardboard box (at least 30cm to a side)
Secateurs (to cut any branches)
A stone or heavy object
If the swarm is in an accessible location, then the following procedure can be used to collect the swarm:-
Whilst wearing protective clothing, approach the swarm without smoke and place the sheet on the ground, below the swarm. Then place the open cardboard box on the sheet.
If the branch is able to be cut, grasp it with one hand to support its weight, then cut the branch and carefully lower it into the cardboard box. If the surface cannot be cut, then the Bees must be knocked off carefully or lifted by the handful into the box.
Carefully turn the box upside down on to the sheet, then use the stone to prop up a corner of the box so the Bees outside can have access.
Making sure to keep it away from the box, heavily smoke the place the Bees had gathered to mask the Queen's pheromones that are left there, this will encourage the remaining Bees to join the Queen in the box.
Once ~90% of the Bees have entered the box, remove the stone, and carefully gather the sheet over the box and tie it securely. The swarm is now ready to be moved to their new home.
Hiving a Swarm
The Swarm will need to be placed within a Hive usually that day and this is best done at dusk as it reduces the risk of the Bees leaving immediately.
There are two standard methods for Hiving a swarm of Bees:-
The Quick Bump method
The Boardwalk method
The following instructions cover both methods:-
Set up the new Hive in this order; Hive stand, Queen Excluder, Brood Box without frames. (The Queen excluder below the Brood Box stops the Queen leaving)
Carefully remove the cloth and lift the box over the empty Brood Box. Sharply bump the box down so that the Bees inside drop down onto the Queen Excluder.
Bump several times to ensure as much as possible that the Queen is now in the Brood Box, then smoke any remaining Bees from the Box.
Gently place the frames with foundation into the Brood Box so the Bees can crawl up onto them without crushing them.
place a Crown Board and feeder onto the Brood Box, then an empty Super (to contain the feeder) and then the Roof.
After 24 hours, remove the Queen Excluder from below the Brood Box.
Set up the new Hive in this order; Hive stand, Brood Box with frames and foundation, Crown Board, feeder, empty super and Roof.
Place a wooden Board (~45x60cm) sloping up to the Hive entrance and cover with a white sheet.
Carefully remove the cloth and bump the swarm out onto the white sheet.
A few Bees will be drawn to the smell of the Wax Foundation within the Hive, and then use their pheromones to call more Bees to the Hive.
Over the next couple of hours, the entire swarm should walk up the board and into the Hive.
Once the main swarm begins to march, they can be left alone.
Remove the Board the next day.
Following up after Hiving
After a couple of days, the swarm should have settled into their new home by using the sugar syrup in the feeder to make lots of comb and the Queen may have started laying worker brood. Any frames which aren't being used by the Bees at this stage should be removed, with the frames in use being moved to one side of the Hive and contained by a Dummy Board.
The remaining space in the Hive should be filled with rags or crumpled newspaper to stop the Bees filling it with Wild Comb. As the colony grows, frames can be added and the empty space reduced as needed.
Note - As there is no brood to begin with, there will be no new workers for three weeks after the Queen starts laying, so the number of Bees in the Hive will drop over this time due to natural losses, and is not a concern.
The video below shows how to capture and Hive a Swarm of Bees:-