These rodents chew combs and frames to make room for building their nests. Mouse urine on combs and frames makes bees reluctant to clean out these nests in the spring. Adult mice move into bee colonies in the fall and usually nest in the corners of the lower hive body away from the winter cluster.
Colonies located in fields or at the edges of woodlots are especially vulnerable.
Mice can successfully build a nest even in a strong colony. They move in and out of the colony while the bees are inactive, and their nests furnish additional protection. Their activity may disturb the bees but the greatest damage is from the nests. Chase away any mice found inside a colony, then remove the nest and restrict reentry. If comb chewing is extensive, replace the frames.