I would like to gain some clarity of understanding about the various comments which have been made in this discussion topic. It seems to be agreed that mice in beehives are a real problem. But there does not seem to be much agreement about the best way to defeat mice which may attempt to gain entry.
Cats – Yes they can catch mice, but they cannot be relied upon to catch every mouse.
Snakes – I am not sure that I want to follow that method.
Mouse guards - made from metal sheet with holes drilled in them, or with slots cut from their edge.
Underfloor entrances - 8mm or 9mm wide. Mice are expert climbers, and I think they may have no difficulty in negotiating a slot of this size.
It also seems that people may change their minds. For example Dani, in her comment #2 said, “You do need a mouse guard”, but then in comment #6 said, “I do not like mouse guards either”.
I wrote to this forum on 7th October (comment #36), in response to Curly’s comment #5. He had said that he did not like mouse guards, because pollen can be knocked from them when bees try to get through the holes. Curly also made a comment in response to my query, saying that it was not just mice but shrews as well which needed to be considered. Perhaps we in Australia are fortunate not to have shrews?
Jenkins made an important comment (#39) about the risk of bees becoming trapped if they were not able to clear dead bees through the holes in a mouse guard. I agree, particularly if we are talking about a hole which is slightly above the level of the landing board. However, I have not seen any reference to what diameter hole may be thought most suitable, whether it should be 6?, 7?, 8mm or something else.
In a subsequent comment (#41), Jenkins said that he had never used mouse guards, but that he would prefer a castellated mouse guard if he needed one, because then there would not be a “step” over which dead bees would have to be lifted.
In attempting to understand and digest all of these various pieces of advice and opinion, it seems that we need to have holes small enough to keep mice and shrews out, but big enough for bees to have easy passage. We want forager bees to be able to easily bring home the pollen, and undertaker bees to be able remove their dead.
I have used a row of non-rusting nails with 6mm gaps between them, across the width of my hive entrances which are 75mm wide and 12mm high. These nails are driven vertically into the base, forming a barricade which is 12mm high. Is there any reason why this gap size (6mm wide, by 12mm high) is not suitable for the task? Could a mouse or a shrew get through it? Would gaps of this size prevent the undertaker bees from doing their job?
