Swarm Alert! – What to do when you see a swarm of honeybees

Swarming can happen throughout the active season, but late spring and early summer is considered swarming season for honeybees in Ireland. We usually encounter a lot of swarming during a spell of hot, dry weather, especially if the weather has been poor leading up to it.

Go straight to Swarming 101 – dos and don’ts

Why do bees swarm?

Healthy honeybee colonies swarm as a way of multiplying when the conditions are right. This is when the parent colony is getting too large for its current space and there is lots of food available to forage on. A swarm is a compete and fully functioning honeybee colony that has left its hive in search of a new home. A swarm will emerge from a colony of bees, leaving a portion of bees behind in the original colony, including either a queen or a queen or a queen cell which will become a queen. Hence the colony is split, and both parts will have what it takes to carry on life as individual colonies.

Components of a swarm

Within a swarm you will have at least one queen bee. You could have either the old queen who headed up the original colony, or you could have one or several ‘new-born’ queens, or what beekeepers refer to as virgin queens. Sometimes several virgin queens will be contained in a swarm. Depending on the size of the swarm, there are also hundreds if not thousands of female worker bees in the swarm. Often you will find some male bees, drones, in with the mix as well.

Bees bring honey for the journey

When a swarm leaves its parent colony, it often does not know where it is going, or when it is going to find a new home. Because of this, the bees will fill their tummies with honey for the journey before they set off. After all, it can be several days before they a safely settled into a new place and they don’t want to travel on an empty stomach! Also, bees build their nest with beeswax, which they make from honey. So, in order for them to get established quickly once they reach their new home, they bring the building blocks with them!

Gathering in trees & waiting

When bees have swarmed out of a colony, they will often initially settle not too far from their parent colony. They might cluster on a fence post, form a ball on a wall or hang from the branch of a tree. This is the clump of bees that we often think of as a swarm, and when people start getting anxious about their presence. But the bees won’t build a nest there, this is just a stop-gap until they have found their new home. When the bees have left the colony and gathered or clustered together, they send out scout-bees to look for possible new places for the swarm to move into.

Looking for ideal cavities

The scout bees are looking for suitably-sized cavities with small entrances that they can easily defend. This is why we seldom see bees build nests in the open in the way that wasps do. (Wasps build a papery outer wall to their nests, and construct the nest within. This means that their nests are protected from the elements, which is why we often see them in trees etc. Bees, on the other hand, don’t make outer walls but build their nest inside already existing cavities. Read more about wasp nests and how to remove them here.)

Research has shown that bees favour cavities of about 40 litres when selecting their homes. Honeybees prefer spots where bees have lived before. They are also attracted to anything that smells like honey, beeswax, propolis or, for some reason, lemongrass! Unless they find a suitable tree cavity, the swarm may have to settle for a chimney, a barbeque, a compost bin or a post-box.

Deciding on the right spot

The scout bees will explore the surroundings for several miles and come back to the swarm and report their findings. They will dance for the other bees showing just how good they think their spot is. With this dance, they try to recruit followers to their chosen spot. If a bee is rightly enthusiastic, she will gather followers, who will visit the spot and see for themselves. They will check it out, measure the inside, the size of the opening, and its general aptness. If they are happy, they too will return to the swarm and dance to recruit followers. This process continues until some unknown quota has been filled. Once relative consensus is reached, the swarm takes flight in near unison, headed for their new home.

Swarms are generally docile

A swarm in full flight is an amazing sight to behold! Although because of the sheer size and noise of it I’m sure for some it can be a little scary! Because of this, in swarming season we often read headlines such as “…followed by and angry swarm of bees…”, “…attacked by swarm…” and the likes. It is, however, important to remember what the bees are doing at this point. They’re moving house. Nothing more, and nothing less. They are simply transporting themselves from their old hive to a new home.

A swarm of bees is usually very docile and nothing to be frightened of. When conditions are right, swarms can often be handled without the need for special equipment. However, they should always be handled by a beekeeper.

Low survival rate for wild honeybee colonies

Unfortunately, only a very low percentage (20-30%) of wild honeybee colonies survive their first winter. This is due to a number of factors including parasites and disease. The parasitic varroa mite being the most prominent. Because of this, it is often preferable if a swarm is captured and rehomed within an apiary. This will increase its chances of survival.

As is often the case, there is another school of thought. This one argues that we should allow for the rewilding of honeybees, particularly the Native Irish Honeybee (Apis Mellifera Mellifera). This would lead to the survival of the fittest. And result in adaptations to different strains of bees so that they can either evolve to coexist with varroa and other challenges, or for the bees to develop traits to combat varroa. (Such as hygienic behaviour, biting off legs of the varroa mites etc.)

Both capturing swarms and rewilding have their pros and cons, and beekeepers and laypersons will most likely discuss this ad infinitum. However, it is unarguably the case that in areas where there are rewilding programmes in place, swarms can be plentiful.

Capturing a swarm of bees

Many beekeepers will be happy to collect swarms. They do this both to increase their colony numbers and to make sure that the colony has the best possible chance of survival. Also, if a swarm is captured before it moves into a chimney or roof it makes it easier for all involved.

If a swarm settles in a roof, to get them out will involve the work of a carpenter, roofer, scaffolder, AND a beekeeper. It does not come cheap. Hence, acting quickly when a swarm of honeybees is spotted it of utmost importance.

Swarming 101 – dos and don’ts 

1. Contact a beekeeper

Contact a beekeeper as soon as you see the swarm. Speed is of the essence. The beekeeper will want to get to you before the swarm has a chance to take off again. It is much easier to capture a swarm hanging off a branch in a tree than it is to remove an established colony from a roof or a chimney. Your local beekeeper’s association will have a list of people who are available to rehome swarms. You can find contact details here and here. You can also reach out to swarms.ie.

2. Take pictures

Take pictures. Images are often better than videos as you can zoom in. Pictures are useful for the beekeeper to establish a couple of things. First if it is honeybees, wasps or bumblebees. Second, if it is a swarm in transit or if they have found a cavity to move into. Third, how big it is so that the beekeeper can bring the appropriate size box to put the swarm into. Fourth, its location and if any special equipment such as ladders or tools are needed to carry out the swarm collection. It will also help to determine if it might be difficult or dangerous to remove the bees.

3. Do not assume someone else will deal with it

Do not assume someone else will deal with it. You might be the only person who have noticed the swarm, or other people might think it’s not their business to get involved.  

4. Do not interfere with the swarm

Do not interfere with the swarm. It is a living organism and does not pose a danger as long as it is not interfered with. Do not use a hose, petrol or throw objects at a swarm. This could cause the swarm to become unsettled and feel under threat. The bees would then be more likely to sting. It is important that the swarm remains intact so that it can be removed and rehomed as a whole. Do not kill it with pesticides etc. Honeybees are extremely important for our eco system and should be protected.

5. Place a bait-hive

If the swarm has gathered in a hard to reach place, you cannot get a hold of a beekeeper or if they cannot get to you immediately, consider placing a bait-hive to capture the swarm. If successful, the swarm can then be removed by a beekeeper. You can make your own bait-hive to encourage the bees to move into it, or get someone to come and put one up. Read more about baithives and how to set them up here: Bait hives to lure swarms – Guest Blog by Keith Pierce

6. Be patient

If you have a swarm of honeybees in your garden, hanging on a branch of a tree, fencepost etc, it is important to know that the bees are only hanging out there (literally!) for a short while until they have found a good place to move. They are unlikely to build a nest or a hive in the open. So there is no need to panic and remove them as fast as possible. It typically takes anything from a few hours to a couple of days for a swarm to find a suitable spot. When they have found one, they will all leave.

What to do if there are bees in a chimney, roof or wall?

If a swarm is heading for a chimney or has just settled in one, light a fire to try to coax them out. If they have already started building comb and the queen has started laying, it becomes more difficult to get them out. Once a swarm has moved into a cavity and started building wax and the queen has started to lay, it is still possible to remove the bees, but you have to remove the honeycomb as well as all the bees.

For a comprehensive article about bees in chimneys and what to do, read this Blog: Bees in Chimneys: Identification, Removal and Prevention

Read more about bee colony removals and cutouts here.

Conclusion: always play it safe with a swarm of bees

If you spot a swarm of honeybees, don’t panic. Stay calm and keep your distance. Swarming bees are not looking to harm you, they are simply looking for a new home. Contact a local beekeeper who can safely remove the swarm and relocate it to a more suitable location. By doing so, you’ll not only be helping to protect yourself and others, but you’ll also be playing a role in supporting these important pollinators. Remember that honeybees play a crucial role in our ecosystem and should be protected whenever possible.

Hanna Bäckmo

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