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I am doubtful about using mesh floors. I have bought one, and it was very expensive – it is going to cost me quite a lot to replace all the floors. The bees look very vulnerable to draughts with the whole of the underside of the hive open. I have found slug trails on the underside of the mesh. All this makes me feel that, at least in winter, the mesh floor might prove quite a drawback for my bees.” (Name & address supplied)

I asked some Cheshire beekeepers — Roy Brocklehurst, David Buckley, Arnold Parrott, Bob Parsonage and Graham Royle - to share their experiences with mesh floors.

Roy Brocklehurst: “I have been gradually replacing my floors with open mesh ones. They are certainly a great boon in treating Varroa. I have not had any negative experiences with them that would make me consider moving back to solid floors. I had one colony not progressing in early Spring. I put back the slide in February to help warm them up. This then needs inspecting regularly and cleaning in order to stop a build-up of debris on it which will go mouldy and/or attract wax moths. I also once had a swarm that didn’t go far – they clustered under the hive on the mesh floor and even built comb there! They were at least easy to collect!”

Bob Parsonage: “It is important that the slide/insert should be at least 2 inches down from the mesh itself. Otherwise the mites that fall out of the hive alive can get back in. Some believe they can jump! They can certainly climb, but at more than 5 cm below the mesh, they seem no longer to sense the bees above, and do not re-enter the hive. Unfortunately, all the manufacturers seem to still make mesh floors with the slide too close.” Bob also thinks that colonies on mesh floors can be slower to build up in Spring: he has come up with a novel solution for this, as he reported in our last issue. If you have a mesh floor with a smaller gap between tray and mesh than this, some beekeepers attach sticky film ( such as sold for backing books) sticky-side-up to the tray. The mites are then unable to free themselves from the tray. An alternative is to smear the tray with vaseline, or some similar substance, although I find this very messy.

All the people I asked are convinced of the need for mesh floors in combating Varroa. Studies in Florida, USA, suggest that mesh floors lead to a reduction in mite-infestation of about 15%, although it is not clear exactly how. They also stress that they are useful in other ways, preventing a build-up of debris on the floor over time, although a yearly inspection and cleaning of the mesh would still seem to be a good idea. They provide the necessary ventilation in winter, without any need to raise the crown-board, or put mesh over feed-holes. However the slide must be removed, to avoid a build up of debris as mentioned above and to let any mites fall free of the hive.

Other studies have suggested yet more advantages—an increase in brood, fatter bees, etc. (see BBKA News No. 163, Feb. 2007, which also has useful plans for constructing a mesh floor on page 8), but without any substantiation to the suggestions.

I think it would be silly to pretend that mesh floors are entirely problem-free. They provide advantages, but we need to learn to live with their potential disadvantages.

One of my colonies (admittedly one prone to propolis) had propolised up a good 100 square centimetres of the mesh before I spotted it and replaced the floor. The propolis was very difficult to remove, and was perhaps a sign that the bees do not altogether enjoy the floor of their home being open to the elements.

Bees seem drawn to the underside of the hive, as with Roy’s swarm, and can often be found crawling about on the mesh as if trying to get in. They can then get trapped or squashed when you slide in the tray. After a very sunny day in February, when the bees were flying as if it were mid-summer, we had a temperature drop to a frost during the night. I found some bees clustered under the floor dead from cold. They looked as if they thought they could enter the hive through the mesh floor, since they could sense the other bees through it. After this experience, I built a baffle on my hive-stand which prevents the bees from being distracted away from the entrance and landing underneath it. This baffle also prevents winter winds from blowing straight in under the hive. Bob Parsonage has a flap at the back of his floors, which closes the gap left for the slide for the same reason.

While we‘re on the topic, hive stands might need to be adapted. Some ways of supporting a hive floor that worked with a solid floor might not work with a mesh one, where it is important that the outer frame is supported, while the space below the mesh is as free as possible, for mites and other debris to fall clear. Most of us in the past had hive stands that sloped forwards, so that moisture collecting on the hive-floor would run out through the entrance. This is now no longer necessary: indeed it might be necessary for your hive stand to slope backwards, so that moisture collecting on the slide can run out to the back opening.

Be careful also in buying mesh floors, to find out whether they will withstand acid and can be sterilised. If, as it seems, we are going to have to treat our colonies with oxalic or formic acid in the future (as well as fumigating combs with sulphur strips or acetic acid), all the hive-furniture needs to have metal parts which are made of something better than the old tin-plate. On the continent, for this reason, all metal parts seem to be of stainless steel nowadays, and I know of at least one British supplier who has moved to stainless-steel mesh. A plastic coating may make the mesh warmer for the bees‘ feet, but it will not withstand scorching for sterilising. Roy Brocklehurst uses a Wickes steam paper-stripper, which he reckons sterilises them as well as cleaning them.

One last question: if mesh floors are so good, and we are all being constantly urged to use them, why do all the manufacturers still sell hives with solid floors as standard?

If you have any interesting experiences with mesh floors, hold strong views about them, or have advice to impart, please let us hear from you for the next issue.

Pete Sutcliffe

CHESHIRE BEEKEEPERS' ASSOCIATION

Apes curamus et nos curant (We look after bees and they look after us)

Founded 1899

Registered Charity No. 227494

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