Key points
- Mice move in during autumn, when the cluster contracts and no longer guards the combs.
- They chew combs, foul the hive and disturb the cluster.
- A mouse guard fitted before the first frosts is usually enough.
- Check the floor at the end of winter.
In autumn, mice look for a warm shelter and food. A hive with a wide entrance is ideal for them: the cluster has contracted in the middle and no longer defends the outer combs.
Signs of presence
- Chewed wax debris and twigs, grass or leaves on the floor.
- Gnawed combs, often on the outer frames.
- Smell of urine, droppings.
- Dead bees decapitated or hollowed out, left by shrews.
- A colony that is restless in midwinter.
Damage
Beyond destroyed combs, repeated disturbance forces the cluster to eat more stores and can weaken it to the point of loss. Soiled combs must be cleaned or rendered1.
Prevention
- Fit a mouse guard or entrance reducer before the first cold nights: an opening about 7 mm high lets bees through but not mice.
- Check there is no other way in: damaged floor, badly fitting crown board.
- Raise hives off the ground and keep the grass short around them.
- Store supers and combs in a rodent-proof room.
Avoid poison baits near hives: they put wildlife and pets at risk.
References
- FAO, IZSLT, Apimondia, CAAS (2021). Good beekeeping practices for sustainable apiculture. FAO Animal Production and Health Guidelines No. 25.