When you first start learning to be a beekeeper, you may be taught that 8 mm is the magic number of the ‘bee space’. Perhaps this is easier to learn when starting to build your own hives. In truth, it’s closer to 6–9 mm.

What is bee space? Imagine an alley between the neighbouring combs within a bee hive, or indeed a natural bee nest. The ‘bee space’ leaves a gap so that bees can work on the opposite sides of the combs and have enough space to move past each other back to back.

This gap or ‘bee space’ is widely considered to be around 6–9 mm (1/4–3/8 in) and is a key principle in the design of most modern bee hives allowing the bees free passage between the frames and the hive wall and above or below the frames.

Bee space is the gap between the frames in the hive, and around the walls and above and below the frames. This gap gives the bees enough space to work on opposite sides of the comb and pass each other back to back.

I’ve read that the variation in spacing might be due to the varying sizes of the different species of honeybee, although 6–9 mm seems a pretty uniform measurement to me.

Why is it important to remember bee space? Because any gap that is too small (less than 6 mm) the bees will fill with propolis, a sticky resinous substance, and any gap that is too big (more than 9 mm) the bees will fill with brace comb (bridges of honeycomb). This, of course, makes it harder to move the frames and boxes of the hive during an inspection.

Beekeeper David A Cushman describes bee space as “A gap in a natural nest bees don’t fill up”. He provides an interesting list of the different types of bee space. He also suggests sometimes the bees will fill small gaps with pollen, perhaps to allow some light to filter around the hive.

Bees filling a small space (less than 6 mm) above the top bars with stick propolis.

But whether it’s 6, 7, 8 or 9 mm, leaving a gap that the bees feel inclined to fill isn’t sensible. So, of course, that’s what Emily and I did. To be fair, this was during the four-week course of Apiguard treatments for varroa, where an eke (sort of an extension wooden frame) creates a space beneath the hive boxes where the Apiguard tray rests on the top bars.

In Melissa’s hive our bees had dutifully built brace comb to fill the gap bigger than 9 mm. And it wasn’t easy to scrape it off the bottom of the super without the help of a hive partner. The bees showed their appreciation of our efforts by munching the oozing honey.

Some beekeepers might consider leaving space for the bees to build brace comb a waste of valuable energy and resources when they could be getting on with other work: filling up super frames with honey or getting ready for winter. There might be some truth in this, but I always enjoy seeing my bees build brace comb. The beautiful curved shapes of freely expressed honeycomb gives an insight into the secret life of wild honeybees.

How do honeybees in the wild know about bee space? Well, I haven’t read much on this, but it seems they weren’t taught it by the beekeepers. Bee space, like the building of vertical combs, is all about gravity:

“Guided by their sense of gravity, though, bees can maintain a comb construction that is vertical, and oriented downward from the roof to the floor. The distance between the comb results from the space a bee occupies when standing on the comb. When moving over the surface of neighbouring combs, bees must be able to pass one another, back to back, without difficulty … and this minimal distance is strictly maintained.” (The Buzz about Bees, Jurgen Tautz, Springer, London, 2008.) Tautz says that gravity receptor organs are found on the bees’ leg joints and between their head, thorax and abdomen, which allows them to build combs vertically down in the dark. Amazing creatures.

Last week we left Melissa’s amazing bees munching on the brace comb honey under the roof, which we hoped they would take down into the nest. Probably an unwise idea as our bees were likely to build more brace comb, but it seemed unfair to take away their secret stash of honey. This week, we would find out what the bees did.

The rainy morning had persisted into the afternoon and though the rain was drying up, the air was too damp and cold for inspections. I arrived to find a small crowd of people at the apiary sheltering under the awnings of the apiary hut. The air was filled with bees, unusual as they don’t often fly over the green netting that separates off the hive area. Perhaps they had also come for tea. In any case, they were happy to fly calmly about listening to the conversation.

Emily came with nuts to feed the magpies and robins. Jonesey was showing off his new iPhone 6 and a new beginner, Emma, was getting to know everyone. The crowd soon dispersed and it was time to see what our bees had done.

In Melissa’s hive I’m pleased to say the workers had done exactly what they were supposed to do! They had taken down most of brace comb honey into the hive. Emily and I cleared up the empty wax and left the remnants around the crownboard holes for the bees to finish up. I saw a little wasp on the crownboard drinking a dreg of honey. Wasps are desperate at this time of year, starving and dying off. I couldn’t bring myself to kill her but couldn’t leave her inside the hive either. I picked up the piece of comb with the wasp and placed it on the roof of an empty hive.

We had fed Pepper’s and Chili’s hives with pollen and syrup though they didn’t seem to need feeding, it has been a very kind autumn for bees. Chamomile’s hive was left to check.

We opened the roof and lifted the crownboard – and the wasps flew in! They must have smelt the scored honey frames feeding the bees above the crownboard. Quickly putting back the roof on the hive, there were at least a couple of wasps inside and many more buzzing around the outside, and trying to disturb the other hives.

I lit the smoker to deter as many wasps as I could, while Emily used newspaper to make the hive entrances narrower. As the wasps cleared we lifted the roof from Chamomile’s hive again and the two trapped wasps flew out. There’s no space for wasps in our bee hives!

That done, we took a walk around the apiary. The rain had stopped, the sun had come out and wasps were still stalking most of the hives. It was time to leave.

Post notes If you’re interested, here’s some more information about bee space.

Top beeway or bottom beeway?
In a natural colony of wild honeybees, bees only leave a distance between the vertical-hanging combs and around the walls of the nest. There is no need for horizontal spaces above and below the honeycomb. But in a bee hive, the beekeeper needs horizontal spaces to move the boxes during an inspection. Here, the concept of bee space is again used by leaving a gap between hive boxes around 6–9 mm. (Collins Beekeeper’s Bible, Ed: HarperCollins Publishers, London 2010.)

“The bee space can either be at the top of the box, over the frames (as in the Langstroth, Dadant and Smith hives), where the bottoms of the frames are in line with the bottom of the box (known as ‘top bee space’) or at the bottom (as in the National, WBC and Commercial hives), below the frames, so that the tops of the frames are level with the top of the box (‘bottom bee space’).” (Collins) Obviously, you can’t mix boxes with top- and bottom-bee space in the same hive or the concept of bee space won’t work.

Which is better? In Guide to Bees & Honey, Ted Hooper refers to this method of spacing as ‘top beeway’ and ‘bottom beeway’. He prefers the ‘top beeway’ design, which he says is most common in America, rather than the ‘bottom beeway’ design used in Britain (my fourth edition of the book was published in 1997, so I can’t say if this is still the trend on both sides of the pond, particularly as many beekeepers like to experiment).

“Top beeway is much more efficient in use and less of a strain on the beekeeper as supers can be lifted back and placed ‘cross-cornered’ on the hive and then slid around into place. With bottom beeway this cannot be done as the edge of the super box would run across level with the top of the frames and would decapitate any bee looking up between the frames and squash many of those walking about on top of the frames.” (Guide to Bees & Honey, Ted Hooper, 4th ed, Marston House, 1997.)

A short(ish) history of the movable-frame hive
American-born Reverend Lorenzo L Langstroth (1810–25) is credited with the invention of the movable-frame hive. It was Langstroth who recognised the concept of ‘bee space’ in a ‘Eureka’ moment, which became a vital component in modern hive design and which now allows beekeepers all over the world to freely move and lift frames and boxes without breaking up the honeycomb. (Collins)

There had been similar bar hives previously, such as the leaf hive invented by Swiss natural historian Francois Huber (1750–1831), and the multi-layered skep hive invented by Englishman Thomas Wildman (1734–81), an experimenter, showman and beekeeper. It is thought that a movable-frame hive was also first designed by Englishman Major William Augustus Munn, author of A Description of the bar-and-frame hive (1844). (Collins)

The theories that lay behind these models may have helped to pave the way to Langstroth’s discovery.

When a space that is too big (more than 9 mm) is left in the hive, the bees will fill it with brace comb (bridges of honeycomb) as shown here above the top bars.

Langstroth was frustrated when his coverboards became stuck down with the sticky resinous substance propolis and like any good beekeeper he sought a practical solution. He cut a recess into the hive box that allowed him to drop the hive bars down to 9 mm below the coverboard, which seemed to solve the problem. Then he thought about similarly adjusting the spacing in the interior parts of the hive to make it easier to work with the bees:

“The critical aspect of his design was the space between the edges of the frames and the walls and floor of the box – an opening wide enough for a bee to pass through and hence termed the ‘bee space’.” (Collins) Langstroth initially used a space of 12.5 mm (1/2 in), before he further discovered that bees leave a 6–9 mm (1/4–3/8 in) space between their combs and the walls in their nests.

A Polish beekeeper Reverend Dr Jan Dzierzon (1811–1906) had put thought towards a system of movable frames by spacing the comb 38 mm (1 1/2 in) apart. But it seemed that 6–9 mm was found to be the most practical movable-frame system and Langstroth’s design is used by 75% of all modern hives sold throughout the world today. (Collins)