In previous posts I have mentioned burr comb from strong hives pushing up and out of the top of the supers. In this post I mentioned the use of hive mats, but didn’t cover their creation.
A hive mat is used to keep the amount of unwanted burr comb in the lid of the hive to a minimum by creating a barrier for the bees to work under. It is critical that adding the hive mat doesn’t restrict airflow through the top of the hive as it will likely lead to condensation collecting and unwanted moisture build up in the hive.
The hive mat design I prefer is called the ‘Mercer Mat’ and is described on the ACT Beekeepers website at the following link.
When cutting the hive mat, the edges should end at the top bars of the outer frames and the ‘shoulders’ of the frame end bars to ensure the bees can still move freely up and around the mat. The centre hole is very similar to a crown board design and limits the condensation build up in the centre of the hive and also provides an opening that can be used for feeding.
The below diagram shows the outside edge of the hive mat with a rough sizing for the centre hole (without rounded edges).
Although lino/vinyl flooring is often recommended for the creation of hive mats, I opted for clear PVC plastic sheeting which can be purchased at your local hardware store (Bunnings in this case). One lineal meter of sheeting was enough to create eight hive mats. For those looking for more natural materials, hessian coffee bags are a possible substitute.
I opted for 0.5mm sheeting to provide some additional weight/strength to the hive mat and to limit the chance of the bees ‘lifting’ the mat and getting between the mat and the top bars of the frames.
The first step is to lay the sheeting flat in the sun as the sheet can be difficult to work with when it’s still curling.
Rather than using any specific measurements for the mat, I measured the PVC sheet using a spare super, and offsetting two sides by roughly 25mm (an inch).
After tracing down two inside edges of the super the mat is ready to cut.
After cutting the mat from the PVC sheet, fold it over twice and cut a section out for the centre hole from the folded edge.
If you cut the correct corner, you will end up with a hole similar to this. The hole should not be cut any wider than the two centre frames in the super.
The outer edge should look something like this, with space around all four edges for bees to move freely. When installing a hive mat in an existing super, ensure the top bars of the frames have had as much debris/burr comb removed as possible to ensure the mat lays flat.
A close up showing where the mat should rest along the end bars. This allows the bees to move up in the galleries between the end bar and the side of the box past the frames.
The benefits of using translucent PVC becomes immediately apparent when inspecting a super that is full of bees (click to enlarge).
Although the mats don’t remain pristine forever, they do maintain their effectiveness and greatly improve the process of opening the hive for regular inspection. Bees above the mat when removing the lid is to be expected.
The only minor issue you may come across is wax being built out from the top edge of the frames to the underside of the mat.
If these wax ‘fingers’ occur on the frames, they should be either removed or pushed back against the edge of the top bar using a hive tool to limit the likelihood that they will injure bees when removing adjacent frames.