What size hardware cloth is best for beehives?
If you are building or repairing your own bee “furniture” you will find there are many sizes of hardware cloth available. Usually, the ones you need are the hardest to find.
Here in the States, hardware cloth is numbered according to how many squares fit in a linear inch. So #5 has five squares to the inch and #8 has eight squares to the inch. In other words, a bigger number means a smaller hole.
Here are some examples of how the different sizes are used:
- #4 won’t restrict honey bees but it is often used for mouse guards.
- #5 allows workers to pass freely, but prevents both drones and queens from passing through. Some people use #5 for queen excluders. However, whatever restricts queen movement also restricts drone movement, so you have to analyze what you are trying to do and what the collateral damage might be. #5 is often used at the entrance of pollen traps because it allows worker passage but knocks off many of the pollen loads.
- #6 allows some workers to pass, but they lose most of their pollen loads. This is less desirable for pollen trap entrances because you want the bees to retain some of their pollen.
- #7 is often used for the collecting surface of pollen traps. Pollen pellets will fall through #7 and become inaccessible to the workers.
- #8 is not good for the collecting surface of pollen traps because many of the pollen pellets are too big to fit through, so the hardware cloth becomes clogged and ineffective. However, #8 is ideal for screened bottom boards, screened inner covers, double-screened boards, moving screens, and screened ventilation ports. It keeps out bees, wasps, hornets, and other small animals, but it allows Varroa mites to fall through. #8 is the most all-around useful size in the apiary.
Some of the bee supply companies sell hardware cloth by the foot or the roll, and it is also available online from a number of sources. I buy it from Amazon.com. The #8 size is listed as 1/8” x 36” x 10’, which may look confusing, but they just list the mesh size as the first dimension followed by the width and length.
It is difficult to make hard and fast rules about the right size of hardware cloth to use because some bees—depending on genetics and cell size—are larger than others. Also, the thickness of the wire varies from one manufacturer to the next, and a thicker wire means a smaller hole.
The above guidelines work pretty well. If you have problems you can experiment with the sizes until you find the combination that works best with your bees.