Nest Structure

The Idea

top bar hive nest

Bees living on their own natural comb.

Broodnest comb is more than a place to store food, raise brood and hang out. It has a structure that is essential for optimum colony function and survival.

When a swarm moves into a cavity, the bees evaluate it’s shape and orientation. Then they build a nest that provides the best possible chance for reproduction and survival.

The resulting broodnest structure compliments changing seasonal requirements and varied colony activities. These relationships are discussed on the Seasonal Dynamics page.

Given a choice, a colony will reject a cavity that can’t accommodate its needs.

The nest can be divided into 3 areas:

  • the broodnest
  • the broodnest core
  • the honey storage area

The Details


When a colony decides to swarm it evaluates a cavity for suitability. Important factors include:

  • cavity size
  • location
  • entrance orientation
  • and defensibility

Their ability to evaluate and act, doesn’t stop once a suitable cavity is found. They continue to make decisions and build a nest whose structure enhances the colony’s survival.

Nest Construction Observations

My top bar hive swarms, cluster in the first one third of the hive, nearest the entrance. Then comb building activity begins on top bars 3 to 5.

Initially, comb building is limited by the cluster’s size. There the bees feed each other and can keep the wax warm enough to work. At this point:

  • most comb is extended horizontally
  • a few central combs are built vertically, just beyond the clusters confines
  • as more comb is built, environmental control between combs requires fewer bees, which frees more bees to work horizontally

Bees build a few large storage and drone cells along the top bars. Then they quickly transition into larger size worker cells. This transition is most pronounced on comb near the entrance.

Worker comb is quickly built there. Later, larger worker size cells and drone comb are completed on the comb farthest from the entrance.

When a few combs are long enough to shelter new brood, vertical comb building becomes more uniform and extends beyond the cluster.


Bees often shift their comb building focus. Sometimes, comb is extended horizontally. Then suddenly, the bees move towards the hive’s front and work comb vertically.

These shifts aren’t strictly related to nectar flow. I’ve seen the bees complete the broodnest core area, near the entrance, during a strong honey flow, and not work in the honey storage area toward the rear of the hive.

Broodnest structure remains consistent even when bees shift their comb building focus elsewhere. Later, a new generation return to finish out the area completing the broodnest structure started by another generation of bees.

How do different generations of bees individually sense what comb is needed? If they couldn’t sense it, each bee’s effort couldn’t produce any structure, as each bee builds only a small part of any one cell.

Natural broodnest cross section.

You can download this Google Sketchup based cross section and take a closer look:


Nest Structure


Bees build straighter comb near the entrance:

  • It’s spaced at 1 1/4 inches
  • and each comb is a close approximation of its neighbor

This is the brood rearing area of the broodnest. Here cells gradually taper from larger sized worker cells:

  • at 5.4mm near the top bar
  • to 4.9mm half way down the comb
  • to about 4.6mm near the bottom of the comb

Comb in the broodnest area is straight and parallel with the ends of larger combs curving toward the cavity’s entrance.

Broodnest Core

Bees kept the smallest cell size areas, near the entrance, open for brood rearing. And they cluster there during the winter. This is the broodnest’s core.

And it’s a important area. Here the bees:

  • detect and remove broodnest peers
  • conserve heat and humidity
  • and efficiently use scarce late winter resources

Honey Storage Area

Typical honey storage area comb.

Farthest away from the entrance, combs quickly transition into a honey storage area. This transition is determined before the colony completes the broodnest area.

The combs:

  • are thicker and wider spaced here
  • contain a few patches of larger worker size cells near a comb’s bottom edge
  • most cells are drone size or larger
  • cell orientation often appears chaotic
  • no small cell sized comb

Combs are parallel in the honey storage area, but straight comb isn’t a priority. Sometimes the direction of comb is completely contrary to the broodnest comb. Here, combs often drastically curve toward the entrance.

Once the broodnest is complete, the honey storage area is extended away from the entrance until an optimum condition is reached. Then only minor broodnest construction
occurs regardless of available space or nectar resources.


The Bees

Reworked comb.

Sometimes a comb is built that doesn’t follow the broodnest structure. Bees are genetically wired to orient and build the right comb, at the right location. But, it’s a delicate process with many factors involved.

Top bar 7 of my hive, was drawn as a mirror image of the adjacent broodnest comb. Drone size cells were drawn down low, on the side nearest the entrance. Worker cells were drawn on the right side. I thought a comb was mistakenly reversed when I worked the hive. Early photos show this top bar had a unique knot. The top bar orientation was correct.

The bees had trouble working with this comb. Some shots show the bees attempted to rework the comb. Combs on either side of this one were drawn rapidly and smoothly finished off. The bottom edges of this comb remained ragged and this comb was never completely finished off.

Can bees make mistakes? I think they can, especially with a beekeepers help. 🙂

Broodnest cross section showing top bars 6, 7, 8, 9.

This comb was within the broodnest core. The lower left part of the photo should be small cell sized worker comb to be consistent with combs on top bars 6 and 8.

The bees tolerated the drone size cell in the upper left of the shot. And they tolerated the larger worker sized cells to the upper right. But they couldn’t tolerate the drone sized cells in the small cell sized broodnest core.

A comb’s orientation and location is important. Or the bees wouldn’t have had problems with this comb.

The Beekeeper

Comb management is a delicate process. The bees balance many factors when building a broodnest. But they don’t have any mechanism to handle comb that:

  • rotates
  • shifts
  • is inserted backwards
  • or disappears

Typical hive management mixes up a broodnest. When I messed up the broodnest structure in my top bar hives, they quickly developed parasitic mite syndrome. And required mite treatments to survive. When I re-arranged the comb to mimic a natural broodnest structure. Mites were seen in those hives, but they didn’t developed PMS.

That’s how important the broodnest structure is. Mess it up and you have messed up the hive.


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15 responses to “Nest Structure”

  1. Juan Carlos Plaza says:

    From Chile. What are the treatment on varroa mite?

  2. Hello Dennis,

    I’ve had top bar hives for two winters here in Nova Scotia, and I’m starting into langs. I’m planning to go foundationless, but was thinking I should regress the bees first. Your articles suggest that may be a waste of time.

    Today, I went through the hives, and along the way, I found a whole comb of just capped drone brood. Following conventional ‘wisdom’, I took it out. I replaced it with an empty bar, and put in a couple other empties along the way.

    Afterward, I began to scratch the cappings and look at the drone brood. Mites all over the place. I eventually scratched it all. I began to feel depressed, as I’ve been trying to figure out how to beat these mites, and there were plenty there. But suddenly I felt as if everything I’m doing is futile. I thought “They know what they’re doing – far better than I do.”

    And I revisited these writings of yours tonight, and I wonder if I should just let the bees do their thing, and quit obsessing over the puzzle of how to beat the mites.

    So, you don’t see a need for regression – just put the bees in the hive, and don’t rearrange the combs or mess with their ordering. Should I avoid foundation all together, or is it okay to do some with and some without?



    • -bW says:

      Hi Adam

      I would need to know more to make a specific recommendation. But if you just have a few heavily infested hives and replacement bees are expensive or hard to obtain, then treat them.
      – use a non-contaminating treatment.
      – I would recommend oxalic acid.

      That gives you time to work out a specific plan of action. And it gives the bees a chance as well. Just don’t poison the comb or your equipment in the process.

      It is just so much easier to work toward a goal with living bees, even if they initially require more help, than it is to let them die and start over again with who knows what.

      Questions about foundation/regression are beekeeping nuances that can be addressed after you get your bees stabilized. Use what you have. What you are comfortable with. Don’t get tripped up on the small stuff.

      After a little experience, you will know what direction to take. And then you can move cautiously and gradually, learning and making the necessary changes along the way.


  3. Hi Dennis, I know you mentioned this someplace (couldnt find it) but when you are getting rid of old comb you said that you do it every 2-3 years and you simply shake the whole colony into a new hive body. My question is:
    What is the best time to do a shake down? I mean the bees have brood at the time of swarming so what do you do with all the brood in old comb?
    Thank you

    • -bW says:

      Hi Che

      Comb rotation is tough in a short season climate like yours or mine.

      It’s easier on the bees to rotate a few old combs out each season. But research indicates that this method doesn’t reduce spore counts in the new comb.

      Shaking the bees into an empty broodnest is more effective, but much more disruptive. I’ve written more about it here.

      Timing? With our short season, it must be done early when the colony is large enough and has enough young bees.

      Brood? If it’s disease free, it can be shared with other hives and culled later when harvesting honey. But I don’t like sharing brood which makes comb rotation problematic.

      The natural cycle in the American southwest is 3 to 5 years. Shaking bees in a short season climate is so disruptive, I’ve pushed comb rotation to the far end at 5 years.

      I’ll rotate comb earlier if problems develop. And I delay rotating comb when a colony continues to thrive.

      In a longer, warmer season climate, I’d rotate comb earlier and more systematically.


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