Sunday, 15 September 2013

How do bees make honeycomb?

Bees build their home out of wax (beeswax!).  Unlike wasps, who collect the material to make their home, bees create the wax themselves.  Underneath the worker bee abdomen there are 4 pairs of glands.  The bee body, like all insects is made of a hard material.  So that the bee can flex its body, this ‘exoskeleton’ is made up of a number of hard overlapping plates, joined by flexible membranes.  The wax glands are hidden in the overlapping area between two of these plates, so that the wax appears as a small flake between the plates.

The bees have to warm themselves up to be able to make and work with wax, because soft beeswax is easier to manipulate.  They also have to eat lots of honey to be able to produce wax.

When they have a flake ready to use, using the stiff bristles on their back leg to hold the wax, they move the flake of wax to their mouth.  This does not always work as well as intended, and the bottom of beehives usually has wax flakes on it, where the bees have dropped a flake!  They don’t seem to bother to pick up dropped flakes, they just create another.

Once the flake is in the bee’s mouth, they chew it to soften it, and possibly add some more chemicals to it.  Then the bee goes to add it to the comb that they are building.

There is no foreman, each individual bee just add more wax where they think that it should go.  To build the perfect hexagonal cell, they first build three rhombuses for the base, because three rhombuses provide a hexagon for the cell walls of one side and a central seam for the cells on the opposite side of the cell.   

The three rhombuses that bees build at the base of a wax cell

Next the bees start building up the side walls on both sides (ie towards us and away from us in this diagram.  When the walls have started to be built, the bees will then start building more rhombuses to make the base of another cell, and so on. 

The bees make cells that are exactly 5.2mm wide for the queen to lay eggs in to make more worker bees (girls).  They create a slightly bigger cell for drone bees to grow in (boy bees are bigger!)

The cell walls are 0.073mm thick to a tolerance of +/- 0.002mm.  If a human was the same size as a bee that would mean making wax cells with walls 10mm thick to a tolerance of +/- 0.25mm.  Do you think you could build something that accurate, with no rulers or tools, out of a soft material using only your mouth and legs?

One trick that the bees use to ‘feel’ the thickness of the wax is to press it gently with their head.  Their antennae touch the wax at the same time and they can feel how much the wax moves, and so how thick it must be.