Why do Honey Bees Swarm?

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A colony of honey bees is an amazing social entity. Thousands of insects working together for the good of the family. In fact, they do some pretty amazing things – one of which is swarming. In this exciting event, half of the colony population pulls up roots and flies to a new home. Doesn’t this seem like a risky move? I think so. But, swarming is a natural behavior of honey bee colonies. If this poses a risk to both halves of the family – why do bees swarm? The answer is a bit complicated.

Large swarm of honey bees hanging in a tree image.

Honey Bee Swarm Mysteries

Swarms are so impressive – you will never forget the first one that you see. In fact, the sight can be frightening to those who are not familiar with the behavior.

Perhaps we have seen too many cartoons of people being chased by bees? Actually, these mobile groups of bees are generally non-aggressive – as long as you give them their space.

Why do bees swarm? Swarming is reproduction on the colony level. The goal of these insects is to produce more colonies. This is accomplished by growing a large population in the hive. The colony then splits itself into two groups.

The large mass of individuals who leave their home in the swarm represent about half of the colony population. In most cases, every type of bee you find in a hive is included in this group.

The current queen usually goes with them. Several queen cells are left behind with larvae-one of which-will become a new replacement queen for the original colony.

Sometimes a very strong colony will “cast” more than one swarm. In the second group to leave, there may be one or more virgin queens.

They will mate and decide who is in charge at the new location. Be careful when harvesting swarms because you never know where the queen will be.

When Do Bees Swarm?

Ah Spring, with its warmer temperatures and new plants budding out – who doesn’t love it. It is a time of growth and new beginnings. This is true for our bee colonies too.

Many of the top flowers for honey bees provide nectar and pollen. The bees see this as a signal to increase brood production-and they do.

As the population grows, the interior of the hive becomes crowded. It’s swarm season!

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A colony can “throw a swarm” at any time during the warm season. But, most swarming events occur in the Spring-as this is the natural time of growth.

Sometimes, it seems a risky move. The mother colony is faced with the need to requeen the hive. The new swarm hive is at risk of not being ready for Winter. But, this is their natural life pattern.

Keep in mind, it is not unusual to find swarming colonies during Summer or even Fall. It is often difficult for the beekeeper to understand why hives swarm in Fall. Many late season swarms fail.

But, nature has a pattern that has worked for millions of years – even when we don’t understand it.

Swarms Are Not Migration

A bee swarm is not evidence of migration. In a swarm event, roughly half of the population stays in the original beehive. There is no back and forth traveling between the old home and the new one.

When all members of the colony leave for a new site, this is called absconding bees. Absconding is most often the result of disease, pests or too much beekeeper interference.

In this case, they do not return to the original location at a later date-as would be the case in migration.

Swarm Preparations Begin

Though it may seem to be so, swarms don’t just happen. The colony begins preparations weeks before issuing a swarm.

This is a risky event for the colony and several things must be done before the swarm can occur.

  • scouting for new homes
  • preparing the queen
  • queen cells

Scouts Search Out New Home Sites

At any given time, a percentage of workers serve as scout bees. Their task involves finding food sources for the colony.

They also have the task of seeking out possible nesting sites. Several scouts will check out new locations while preparations continue inside the hive.

Slimming the Queen

In most cases, a well developed laying queen is too large to fly – she must be slimmed down. Workers feed her less so she can prepare for flight. Her egg laying will also slow down right before leaving.

Queen Cells are Built

As the colony prepares to swarm, special cells are formed and cleaned – queen cups are the first stage of the timeline. The cells are often along the bottom of frames but they can be on the face of the comb too.

An interesting fact about the queen bee – she is needed to get a replacement underway. Once a firm decision has been made to swarm, workers prepare cells where the queen lays fertilized eggs. Now they are called “queen cells“.

Larger than regular brood cells, peanut shaped queen cells hold the future queen for the mother hive. Several queen cells are constructed with developing queens in each. Only one will survive.

Once you see these the colony is definitely in swarm mode and the beekeeper must interfere or prepare to catch the swarm.

Queen cells in a recent swarmed colony one of the cells is open image.

Swarm Leaves the Hive

Several terms are used in beekeeping to describe the actual event when the swarm leaves. A hive “casts a swarm”, “throws a swarm”, “a swarm issues from” – you pick, they all mean the same thing – the bees are leaving!

We don’t know everything about honeybees. One mystery of honey bee swarming is – what is that final trigger than makes things happen? But, when everything is right and all preparations completed, the colony is ready.

On a warm day usually between 10 A.M. and 2 P.M. the hive becomes very active. A strange roar can be heard inside.

Worker honey bees run around inside the hive in a frenzy. They chase the queen and keep her moving until she is willing to leave the hive. Thousands of bees pour out of the hive entrance and fill the area. At first, they fly around and around.

Temporary Transition Spots

Then, the swarm will sit down somewhere near the hive. It is often a nearby tree bush or other natural structure chosen for the temporary stop.

But, sometimes their choice can be very surprising such as a mail box, a fence or a car! If you are involved in urban beekeeping you must be extra vigilant about swarm control. People unaccustomed to honeybees tend to get excited over this.

The cluster remains in this temporary resting place for a brief time. Perhaps, a couple of hours or even overnight.

Scouts fly to and fro from the hanging swarm to possible new locations. They return to the cluster and perform bee dances on the outside – trying to recruit others to vote for the location they have found. When most of the scouts come to a consensus or agreement – it will be time to go.

During the phase, the beekeeper has a chance to capture the swarm – hurry! Eventually, the swarm will move on to their new home.

Swarm of bees flying over homes in city.

Swarming Bees are Docile

What to do if you see a swarm? These insects are not aggressive unless provoked. They are protective of their hive but most swarms are known to be very docile.

They have no resources (hive, honey, babies) to protect. For this reason, with a swarm you are less likely to experience a sting – the bees have no reason to sting.

However, proper safety should always be used to prevent stings – bees are wild insects. If threatened, they will defend themselves.

Keep children and pets away. If you see a swarm hanging in your yard, call the local beekeepers association.

Preventing Swarms

Beekeepers love seeing swarms, as long as, they come out of someone else’s hive. Most beekeepers try to prevent swarms. A colony that swarms will usually produce less honey that season.

Many books have been written on bee management and swarming bees. You will hear of numerous methods for preventing swarm behavior.

Some of the tactics work some of the time. None of them work all of the time. Beekeepers do have some techniques that we use to reduce and hopefully prevent swarming .

When managing beehives for honey production, swarm control is very important. However, we must remember that we are fighting natural bee behavior.

Catch a Honey Bee Swarm

Because swarming is a natural thing, sometimes you just have to roll with it. Spend some time setting up a swarm trap. If you can catch it, you are preventing them from getting away completely.

Traps should be check regularly to make sure they are in good condition. The best swarm trap in the world is worthless if the bees fail to go in it.

Beekeepers employ different methods of swarm lures and bait to attract swarms. It never hurts to encourage a swarm to come into a box.

Don’t be afraid to make adjustments to your honey bee swarm trap or location. Don’t be overly focused on what the books say. You never can tell what bees will do.

If you are lucky, bees will eventually move in! Once you have lured the swarm into your trap, it will be time to plan on a permanent box for them.

Small bee swarm moving into a bait hive or swarm trap box image.

Learning how to catch a honey bee swarm involves more than just watching, attracting and trapping. After you get the bees in the trap, you have to get them out again..LOL

You will never forget your first big swarm catch. I remember my biggest swarm catch like it was yesterday.

The good news is that in most cases, a colony that swarms is strong and productive enough to want to increase. Sickly colonies are not likely to have the resources needed for reproduction on this level.

Perhaps we beekeepers spend too much time trying to prevent swarms. Honey bee swarming is a vital part of bee survival. It is important to understand that we work with our bees, we do not control them.

Our best hope is to work with the natural tendencies of the colony. And, take a moment to appreciate the majesty of the process. May your bee swarm season be a blessing.

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Are Swarms Dangerous?

No, in general honey bee swarms are very docile.

The bees do not have any stored food or baby bees to guard.They are in a transition phase with all of their thoughts on getting to their new home.
bee swarm on fence

What Should You do If You See a Swarm of Bees?

In most cases the swarm will move on in a few hours or the next day. If the bees remain in place, do not try to kill them.

Call a local agricultural office or local beekeeping club – some local beekeeper would love to come collect it.

Why do Bees Swarm in a Tree?

When you see a large clump of bees hanging in a tree. This is a temporary transition spot.
If they can agree, they will soon move on to their new home.

large bee swarm hanging in a tree

Will Bees Swarm Without a Queen?

Basically, no. A swarm would serve no purpose with having a queen bee. However, the swarm may contain a virgin queen who has not mated yet.

What to do if a Swarm of Bees Attacks You?

That’s an easy one – run. A true swarm is very unlikely to attack anyone unless they have been provoked.

However, if you are ever in a situation where a swarm of honey bees decides you need to go – go.

Walk away quickly and get to an interior space – inside a house or even in a car. It is better to be in the car with 10 bees than outside with 10,000.

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