How Do I Prevent Swarms?

Great question—and likely, an especially hot topic for this year because the unusually warm weather has encouraged faster build-ups.

Unfortunately, the only guaranteed way to prevent swarms is to not have bees. Luckily, there are some things you can do in an attempt to minimize swarms.

Next month we’ll be discussing swarm control in depth, but until then, here’s some insight on swarming and prevention from expert beekeeper Michael Bush, whose a website is

There are two main types of swarms: reproductive swarms and overcrowding swarms.

Overcrowding swarm: Since it’s the simplest and can happen anytime, let’s briefly look at the overcrowding swarm. The factors that seem to contribute are:

  • No place to put nectar so it gets stored in the brood nest.

    • Prevention: add supers.

  • Honey or pollen clogging the brood nest so that the queen has nowhere to lay. Prevention: remove combs of honey and add empty frames so that the bees will be occupied drawing wax and the queen will have somewhere to lay and the bees will have more room to cluster in the brood nest.

  • No place to cluster near the brood nest. The bees like to cluster near the queen (who is in the brood nest) and this clogs the brood nest making it crowded.

    • Prevention: Slatted racks give room to cluster under the brood nest. Follower boards on the outside give room to cluster on the sides of the brood nest. These are a 3/4" wide top bar with a sheet of plywood or Masonite or similar material in the middle the size of a frame. One on each end replaces one frame in the brood nest.

  • Too much traffic congesting the brood nest.

    • Prevention: a top entrance will give foragers a way in without going through the brood nest.

So basically, if you keep supers on and provide ventilation you can prevent an overcrowding swarm.

Reproductive swarm: The bees have been working toward this goal since last winter. The first mistake people make about preventing swarms is they think you can just throw on some supers and they won’t swarm. But they will. Yes, it’s nice to have room for them to store the honey, so the supers are helpful, but bees intend to swarm and the supers will not deter them from the plan to do a reproductive swarm.

When pollen starts coming in in the spring, bees rear more brood to build up. They also start using up the honey they have stored. This is used to feed brood and it also makes room for more brood.

When the bees think they have enough bees they start filling all of that back in with honey, both to stop the queen from laying, and to have adequate stores in case the main flow doesn’t pan out. As the brood nest gets backfilled it makes more and more unemployed nurse bees. These nurse bees start doing a keening buzz that is quite different from the typical harmonious buzz you usually hear—more of a warble.

Once the brood nest is mostly full of honey they start swarm cells. About the time they get capped the old queen leaves with a large number of bees. Even if you catch the swarm, the hive has still stopped brood production and has lost (to the swarm) a lot of bees. It’s doubtful it will make honey. If there are still enough bees, the hive will throw afterswarms with virgin queens heading them.

If I don’t catch them in time, once they make up their mind I always make splits because not much will dissuade them. Destroying queen cells only postpones the inevitable at best and most likely will leave them queenless. My guess is that most people destroy the queen cells after the hive has swarmed without realizing it.

If you catch them trying to swarm between about two weeks and just before the main flow, a cut down split with the old queen and all but one frame of the open brood in a new location is a nice swarm prevention method. Leave the old hive with all the capped brood, one frame of eggs/open brood, no queen and empty supers. Usually, the old hive won’t swarm because they have no queen and hardly any open brood. Usually the new hive won’t swarm because they have no foragers. This is best done just before the main honey flow.

I often just put every frame that has some queen cells on it with a frame of honey in a two frame nuc to get good queens.

But, of course, the real object is to avoid the swarm and the split (unless you want to do the cut down split) so you’ll have a bigger stronger hive that will make more honey.

Opening the Brood Nest

This, of course is what we want to do; interrupt the chain of events. The easiest way is to keep the brood nest open. If you keep the brood nest from backfilling and if you occupy all those unemployed nurse bees then you can change their mind.

If you catch it before they start queen cells, you can put some empty frames in the brood nest. Yes, empty. No foundation. Nothing. Just an empty frame. Just one here and there with two frames of brood between. In other words, you can do something like: BBEBBEBBEB where B is brood comb and E is an empty frame.

How many you insert depends on how strong the cluster is. They have to fill all those gaps with bees. The gaps fill with the unemployed nurse bees who begin festooning and building comb. The queen will find the new comb and about the time they get about 1/4” deep, the queen will lay in them.

You have now “opened up the brood nest.” In one step you have occupied the bees that were preparing to swarm with wax production followed by nursing, you’ve expanded the brood nest, and you’ve given the queen a place to lay.

If you don’t have room to put the empty combs in, then add another brood box and move some brood combs up to that box to make the room to add some to the brood nest. In other words, then the top box would probably be something like EEEBBBEEEE and the bottom one BBEBBEBBEB. The other upside is I get good natural-sized brood comb.

A hive that doesn’t swarm will produce a lot more honey than a hive that swarms.

Nationally recognized expert Michael Bush is coming to Field Days this year! You’ll soon be able to make your reservation for this space-limited event via the website or by phone.

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