One of the more aesthetically pleasing sights in nature is the structure constructed by bees to form the basis of their home - honeycomb. We all know this iconic pattern well. While it originates in nature, it is such a successful design that many manufactured products have come to mimic its shape.
The hexagonal cells that form honeycomb are around us in many ways, but as beekeepers we become intimately familiar with them through our beehives. Each individual cell has a story to tell, through the myriad ways in which it can be used by bees.
The concise and orderly pattern of comb is a symbol for structure, order, utility and strength - and with good reason. This pattern hasn't occurred by accident. Bees have discovered a way to build their home that serves them incredibly well.
Let's look at the secrets and purposes of honeycomb in beehives.
The Making of Beeswax
Beeswax - the material uses to make honeycomb - is a truly extraordinary material, with some fascinating properties. But how do bees produce the wax they need to make cells?
As we discovered in The Anatomy of Bees, worker bees have 8 pairs of wax glands under their abdomen. These glands produce small, flat wax "scales" of up to 3 mm long and 0.5 mm deep. When a worker creates comb, she scrapes a wax scale from her abdomen using the spines on her pollen basket and passes them to her front legs.
Holding the scale in place, she will then mix it with saliva by chewing with her mandibles. This adjusts the malleability of the wax, making it more suitable as a building material from which each individual cell is built. Repeated tens of thousands of time, these cells form the comb in a beehive. That comb is used for many essential purposes by bees.
Nectar and Honey
Bees need a place in which to establish their home, both in nature and in our hives. Their choice of wax-based, hexagonal cells is a simple approach but one that affords them many benefits. Before we look at why bees choose this approach, let's first consider the purposes in which they use this comb.
The most obvious and well-known reason bees build comb is as a place to create and store honey. We do, of course, take indirect advantage of that eventually around the breakfast table. But while bees deliver that sweet treat to us, they obviously don't do it for our benefit!
Honey is an essential resource for the bee, particularly essential if they are to survive the winter months. During the cold months, bees are unable to venture away from the hive to gather nectar and pollen. They must, therefore, be totally reliant on the honey resources they have built up within the hive, as they form the "winter cluster".
Bees use cells to create honey in two phases. First, nectar foraged from flowers will be placed in cells and left uncapped. This allows the water content of the nectar to be reduced. Bees help this process along by fanning their wings over the open cells, thus passing air over the nectar.
When the water content of the nectar has reached the right point, bees will cap the honey. This means covering the cell with a thin layer of wax, ensuring the honey stored in the cell will maintain the same water content. Capped honey is recognizable by a white seal over each cell. At that point, the bees have produced and stored honey.
The bees that collect nectar from flowers do not directly deposit it into cells when they return to the hive. Rather, a receiving bee will accept it and retire to an appropriate part of the hive for "processing", before placing in a cell.
While honey is an essential source of carbohydrates, bees need a balanced diet. For proteins and fat, they collect and store pollen. As a beekeeper you will regularly see bees returning to the hive with colored bundles of pollen, one of the more enjoyable sights as you observe your bees. You will see cells in your hive that have colors reflecting the type of flowers visited.
Interestingly, while incoming bees pass nectar to other bees for processing, this is not the case with pollen. Instead, a bee with pollen will move directly to a cell and store it herself.
Here's a great video illustrating just that.
When we look at comb created by our bees, the regularity and consistency of the pattern made by the cells is very evident. Many of cells are the same shape and size. However, as with most things associated with bees, all is not quite as simple.
The cells built for each caste differ, as follows:
- Worker Cells: Most cells in the brood area will be intended to raise worker (female) bees, the smallest of the three castes.
- Drone Cells: Drones are larger than worker bees and therefore the cells in which they are created are also larger. The cap on drone cells is more domed than that of worker cells, which helps with identification of drone cells.
- Queen Cells: These are often called queen cups and are a different shape and size altogether, as compared to worker or drone cells. Queen cells look somewhat like a peanut hanging from the comb. Their presence may be cause for alarm and signal some potentially negative scenarios, though this is not always the case.
An important element of the beekeeper's skill set is an awareness of where brood cells would normally be created, their numbers and so on. Interpretation of the brood area is a vital part of any hive inspection.
There is one other benefit to the use of comb that is rarely considered - as a communication medium. Bees have a number of ways to communicate, using most of their senses. Pheromones, for example, are an essential mechanism through which bees determine the health and productivity of the queen. Other pheromones are used as an alert to danger.
One of the less obvious ways to communicate, though, lay at the very feet of bees within the hive. The cells on which the bees live - and walk - can conduct vibrations. Studies have shown that bees can detect and respond to this across the hive.
Some beekeepers maintain that this is a reason to avoid the use of man-made foundation, which may not have the same qualities as natural comb.
Why Hexagonal Cells?
There has often been debate about why bees create their honeycomb using the familiar hexagonal shape for each cell. Some associate this with "bee intelligence", some to an eye for a beautiful pattern, some to evolutionary forces and so on.
There is likely a simple physics-based explanation and maybe a little math. But regardless of why bees take this approach, the fact that they do remains an amazing observation. Let's take a deeper look.
Whether by "intelligence" or otherwise, the creation of hexagonal cells has many benefits. Perhaps the most obvious one is that unlike, say, circles the hexagon is a shape that can be combined leaving no gaps. That said, other shapes like the square and triangle share this property, so perhaps there are other reasons.
Beyond the obvious efficiency of space, there is also a benefit in terms of "cell builder efficiency". If a bee creates a cell of a random shape, the next cell can still adapt to its shape. However, the second cell can't be created until the first cell is complete. The consistent use of a hexagonal cell means that bees can rapidly and efficiently build cells, safe in the knowledge that the next cell will join it comfortably. That consistency, across the entire hive, has a major impact on the speed with which bees can build their comb.
However, there is another very important benefit to the use of a hexagonal cell.
Compared to the other shapes that leave no gaps (such as triangles and squares), the hexagon creates comb with the least required volume of structural material i.e. wax.
This was the subject of considerable debate for many years. A mathematician at the University of Michigan, Thomas Hales, eventually produced a mathematical proof that the hexagon is the most efficient approach, for a given volume of building material.
So, we need the brightest minds to prove something bees seem to know intuitively!
This is important. As we have seen, the production of wax takes time, energy and the collection of materials. These are valuable resources to bees and so the minimization of the use of wax is essential. The hexagonal shape of the cell addresses that need.
While we can debate how and if bees "know" why a hexagonal cell is an excellent choice, it is a fact that they have chosen an incredibly efficient and beautiful way to build their homes.
Decisions for the Beekeeper
Much of the life of the bee is objective and effective. It is how nature works and we can easily accept the outcome. The issue of cell size is an aspect of beekeeping that greatly enhances its enjoyment, while also having the ability to infuriate.
Cell size is a topic of much debate between beekeepers! We will sum this up on one simple statement:
Put 10 beekeepers in a room and you will find 11 opinions
We joke, of course - but only partially!
There are indeed many opinions among beekeepers. The use of foundation is one such important topic. It is a debate that can keep beekeepers arguing all day! For now, we'll just introduce you to the controversy at a high level.
Bees have lived and survived successfully in nature for millions of years. They are incredibly robust and able to fend for themselves. Beekeepers place them in an artificial location, namely the bee hive. Then we ask them to live a natural, productive life.
It isn't always so simple.
The topic of whether to use man-made foundation - the substrate on which bees to create their comb - is an open, ongoing debate. Many beekeepers with a bent towards a more natural form of beekeeping prefer to simply provide a rectangular frame, on which bees can create their own foundation. The bees will then use wax to create cells forming a surface of entirely natural comb. This approach is referred to as foundation-less beekeeping and is a key tenet of the broader philosophy of natural beekeeping.
Also common is the use of man-made foundation. Typically, this is a plastic frame, often covered with wax. The foundation is imprinted with a basic structure of cells and bees will build their own cells on top of this. The idea here is that bees have a significant head start, in that they do not need to expand time and energy building a solid foundation. This allows them to instead focus merely on the cells covering the foundation.
Proponents of foundation-less beekeeping argue that the decision about cell size is made for the bees when a man-made foundation (with a cell structure imprinted) is provided - and that is far from natural for the colony.
The use of foundation is more common than foundation-less frames. But the debate continues.