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Swarm Prevention and Beginner Splits


Like many organisms, a honey bee colony is on a mission to reproduce after emerging from winter, and it does so by dividing. Reproduction is the basis for existence, and such a primal survival instinct is not easy to suppress. The multifaceted nature of the swarm impulse suggests the need for a multifaceted response. Adding a box is not the only option, nor is it always the best one.

Of note is the potential of swarm prevention to have unpredictable and far-reaching evolutionary consequences. The wisdom in suppressing the reproductive behavior of a honey bee colony is worthy of discussion and needs to be researched. Does depriving the colony of the swarming process negatively impact other behaviors? Something similar has been observed in the selection for the pollen hoarding trait, which was found to be genetically intertwined with a host of seemingly unrelated behaviors. We should learn about the consequences of taking away the swarm impulse to be certain we're not making a mistake.

For now, preventing a swarm is best viewed as a component of the beekeeper’s higher springtime purpose, which is more completely a matter of reproductive guidance. From this perspective, the goals of colony and keeper are aligned. Absent the reproductive guidance of the beekeeper, a colony is likely to divide just days before the nectar starts to flow by swarming into the living room wall of the next closest house. Honey harvest, best queen and exchanging pleasantries with the neighbor are no more. In the absence of any evidence that suggests future regret, it’s best to contain reproductive events within apiary boundaries by performing well-timed, preemptive splits.

In the simplest terms, it's still not real simple. A colony swarms when a period of rapid expansion has become unsustainable due to the occurrence of internal limiting factors (i.e. not because the nectar flow has ended). These limiters can also be considered triggers:

  • high population density – the hive reaches full capacity

  • brood nest congestion – a lack of available brood cells for the queen to lay

  • reduced transmission of queen pheromone – the combined result of the first two conditions

  • worker age distribution – a high proportion of young bees and unbalanced division of labor

  • reproduction optimization – the queen has maximized her daily output

Each of these factors alone does not reliably cause a colony to divide, but this multifactorial aspect of the swarm impulse means it might, even if there’s enough space to accommodate a higher population density. For example, brood nest congestion can prevent further growth of the population due to a lack of empty cells for the queen to lay. Adding a box won’t add brood cells any sooner than the colony adds swarm cells, so it won’t prevent the swarm. A better option is to make room in the brood area by removing frames of honey or capped brood and adding drawn comb. Conversely, if the colony is simply too populous for the available space, expanding the brood nest won’t change anything, but adding an empty box should keep the colony intact, at least temporarily (assuming queen rearing hasn’t started). There will be plenty of times when neither of those responses will be adequate.

Notably absent from the list is queen age, since it has been well-established that a queen is more likely to swarm in her second year. This may reflect the older queen’s lower maximum egg output (reproduction optimization) or natural decline in pheromone production (reduced transmission). If that’s true, the prediction would be for a colony headed by a poorly mated queen to swarm at a lower population threshold (provided she is still mated well-enough to initially expand the colony). An interesting project would be to evaluate the fertility of mother queens to determine if the size of the swarm faction correlates with the queen’s fertility.

There are also Implications for splits. A higher proportion of young workers (worker age distribution) beyond some threshold may result in the construction of swarm cells when combined with other swarm stimulus. Does it also mean that a higher proportion of old workers has a suppressive effect on queen cell construction? This could help explain why a laying worker colony may finally start rearing a new queen only after several frames of worker brood have been donated over the course of a few weeks. It may also explain (at least in some cases) why a split doesn’t always raise a new queen. Maybe it was heavily weighted with older bees that are not inclined to rear brood (although they can). Adding young bees or capped brood may provide a solution, because it will lower the average age of the population.

The take-away here is that successfully predicting which of the five limiting factors is likely to occur first can reveal what action by the beekeeper will be most helpful for guiding colony reproduction, either by promoting it with a split or preventing it for maximum honey production. By the time a swarm issues, most or all of those factors are observable, so the window of opportunity is short. There isn't any harm in adding a box anyway. You could add more that one if you're going to be away for awhile. Just keep in mind a swarm could still be lost due to other factors. If prevention is the goal, the mission is to eliminate all limits to colony expansion. This often but not always means that adding another box will keep the colony whole.


This guidance is meant to simplify the process of splitting a hive for those with little or no experience and no mentor to guide them. It won’t answer all your questions, but it might answer enough of them to get started in the right direction. Let it serve as a platform from which to build a better understanding moving forward. Consult multiple resources. We're all in love with our own opinions so best to ask around.

The first thing to know is that swarming and spitting are nearly synonymous, because both result in colony reproduction. That is the primary goal of an overwintered colony – to reproduce. It does so by dividing. It’s usually in the beekeeper’s interest to prevent such a swarming event, and represents one of the few occasions when the objectives of colony and keeper are not aligned. Note that attempting to impose your will on a colony of honey bees is totally pointless. They are far too stubborn. It’s better to just submit to their need to divide and focus instead on controlling the timing and outcome of colony reproduction by performing a split.

Keep it simple the first time around, and don’t worry if another hive is not what you want. Plenty of others do, so you can easily sell or donate the offspring. If your bees are struggling to expand, forget about swarms and splits, and work on identifying and addressing the problem. Take advantage of the Utah Apiary Program, a coordinated effort by the state and counties to help beekeepers diagnose problems in their hive at no cost to the beekeeper. The service is provided by either a state (801-538-4912) or county (801-874-2999) inspector, and all diagnostic testing is performed by the UDAF Entomology Laboratory. If outside Salt Lake County, visit the UDAF website for the contact info of your county inspector.

How, when and where to split:

How – There’s a hundred different ways. The simplest is to make sure both sides have at least one frame with eggs and one frame with pollen and honey. You don’t even have to find the queen. For a larger split, add more brood and food.

When – Upon finding queen cells or after the start of drone rearing and before the start of the nectar flow (mid-May). Understand that she doesn’t mate with her own drones – it’s just a rule of thumb. Also, wait for the cold front to pass and temps to stabilize above 45-50F.

Where – Wherever you like. Foragers will fly back to the original hive and nurses will stay with the split. Add extra bees to the split to compensate. This isn’t necessary with one or two miles of separation, in which case the foragers can’t find the old hive so they return to the split. If the book says three miles, they're probably not referring to an urban setting.

For a more calculated approach, and to ensure a honey harvest:

Plan to split your colony during the first week of April. Transfer three frames of brood and your queen into a new hive (be sure to leave the original colony with eggs to raise a replacement). Three frames of brood and a laying queen need just over a month to cover twenty frames and produce a surplus. By splitting at the start of April, the new colony will have time to reach full strength by mid-May, with a week or so to spare for bad weather. If you must delay splitting until the second week in April, you’ll still be in good position to produce a harvest. Providing a mated queen for the queenless half could double the harvest. Keep in mind, however, that disease resistance is local, so it’s probably better to let them raise their own. It’s good experience, cheaper and more interesting

Some important things to remember:

1. Always make sure both sides have eggs (even if they have a queen) and food (both pollen and honey)

2. Load the split with extra bees by shaking in a few brood frames or more (otherwise provide 1-2 miles separation).

3. Consider the weather, and make sure both sides have enough bees to cover their brood at night.

4. If splitting with queen cells, failing to destroy all but one of them may result in a swarm. In fact, any split could eventually swarm.

5. Splitting is easy. Your bees are eager to correct your mistakes, so you won’t even know you made them.

6. Treat before splitting. The split mites aren’t likely to be in proportion to split bees. One half will experience an increased load.

7. It's supposed to be fun. And it is!

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