09/26/2026
You've weighed the stack. You've got the insulation on. The moisture plan is sorted. There's one more entrance to deal with β and it's the one at the bottom, the one that stays open all winter.
Late September is when field mice start scouting for winter shelter, and a beehive checks every box for them: warm, dry, full of comb, and guarded by bees that are about to slow way down and stop patrolling. Once a mouse is in, a winter cluster isn't in a position to evict it. What comes out in spring can be a box of chewed comb and nesting debris instead of a colony.
The fix is old and simple: reduce the entrance to roughly 3/8 inch β enough room for a bee, not enough for a mouse β and use metal over wood if you can, since a determined mouse will just chew through a wooden reducer. Don't seal it shut, though. Bees still need airflow and still take cleansing flights on warm winter days.
It's a five-minute job that's easy to forget until it's too late to fix. Full overwintering system β weight, structure, moisture, and now the entrance β is on the blog. We're always happy to help, even if you didn't get your bees from us. Call or text 701-809-0153.
How we overwinter colonies in four-high five-frame stacks: 20 frames, 15 resource and 5 nest, 200 lbs by Halloween, insulated and facing south.