Mouse guards:
Every year in October, I put mouse guards on the flight holes of my bee colonies.
I have learned from experience. A few years ago, I lost bee colonies because mice had overwintered by eating both the wax and the bees.
The bee colonies that survived the unwanted mice were very small and did very poorly during the winter.
Before that winter, I don't think I had observed any losses or lost bees due to mice, so I don't know why it happened then. It wasn't a particularly harsh winter. The mice had just acquired a taste for the bees and wax.
Traces of mice in the hive:
If you see the rear ends of bees lying on the bottom of the hive or outside the hive, then there have been mice. They only eat the front part of the bees and not the rear part, and I think this is because it contains the bee's faeces.
The mice use the flight hole to get into the bee colony. They eat both wax and bees. During a long winter, they can eat almost an entire bee colony, but more typically they eat 2-10% of the bee population.
When:
When to put your mouse guard on is probably a matter of preference. For me, it works to put them on when I have fed the last portion of feed. This also allows me to clearly see that the bee colony has finished feeding because the guard is in place.
If you have several bee colonies in your apiary, this also gives you a quick overview of which ones need more feed, so you don't have to check on the ones that are finished.
I remove the grid again when I do my spring inspection. At this point, there are no longer any problems with mice.
Mouse grid:
What should a proper mouse guard be able to do?
If you use a grid with too small a passage, the bees will lose pollen when they return from their flight, which is a waste of resources.
A grid with too large an opening allows mice to pass through.
After some experimentation, I have found that the best size is 8 mm. A queen grid is usually around 5.3 mm to 6 mm, so it is not suitable as the bees lose their pollen sacs from their legs when they pass through.
My mouse screens:
I make my mouse screens from galvanised aviary mesh that is 8x8 mm with a wire thickness of 1 mm.
I have bent them into a shape that makes them quick to install and remove again.
The grid is made for Swi-bo Langstroth bases.
They can be purchased here on the website, see under the menu 'Bee equipment'. Or use the link. Buy mouse guards
Good luck with your work:
After spending late summer and autumn building up large, strong bee colonies with feed and protein, it would be a shame to ruin all that work by not putting mouse mesh on the flight board. So, good luck with your work.
Last updated: 19. jan. 2026
