UPDATE: I don’t use half-inch mesh anymore because shews can easily slip through it. I use 6mm (quarter-inch) mesh now.
My patented mouse-proof entrance reducers worked well enough for us last winter. They’re cheap and easy to build. But I decided to try something different this year. It’s not as cheap and easy, but neither is it complicated. I simply stapled some half-inch mesh over the entrances of the hives like this:
I got this tip from a Brushy Mountain video (I just can’t remember which one). I chose this method for mouse-proofing the hives this winter because it provides better ventilation. I just hope it doesn’t provide too much ventilation by allowing more cold wind to blow through the hives.
The bottom boards of our over-wintered hives were thick with dead bees by the time spring rolled around, probably because the reduced entrances were so small that they got clogged up. The mesh will make it easier for the bees to pull out their dead. But I wonder: Is half an inch small enough to keep mice out? It doesn’t look that small to me, but if it’s done at Brushy Mountain, I assume it works.
UPDATE (Oct. 20/11): I found the video from Brushy Mountain. It’s called Over Wintering Bees and Beekeeping Discussion Panel. It’s a downloadable Windows Media Video file, and here’s a screen shot from the 16-minute mark where Michael Palmer talks about what’s needed to wrap a hive:
Michael Palmer doesn’t staple the screen on like I did. He bends it like this:
And then shoves in under the entrance like this:
The springiness of the mesh holds it in place. I don’t have a good pair of wire cutters and bending the mesh only added to my difficulties, so I just stapled it on. Bending it in, if you can do it, is probably a better way to go about it. But anyway, it looks like a half-inch mesh is fine for keeping the mice out.
I’ll update this post in the spring of 2012 and let you know how it worked out.
P.S., Michael Palmer’s portion of the video seems applicable to Langstroth hives in Newfoundland. He wraps his hives with type 15 asphalt felt and puts a piece of hard insulation over the inner cover — exactly like we did last winter (and our bees got through the winter a.o.k.). East coast Newfoundland winters are probably wetter than his northern Vermont winters, but it’s close enough.
Oct. 01/13: I’ve had no problems mouse-proofing my hives by stapling on the half-inch mesh. As far as I can tell so far, it works.
Jan. 15/14: Make sure to get the mesh on early. See my Mice in a Hive post to see what mouse damage looks like.
Jan. 31/15: I’ve found tiny shrews in a few of my hives over the past two winters since I moved my hives to a new rural location — and subsequently lost the colonies. I may switch to a quarter-inch mesh next winter as described by Michael Bush, or I might block up the bottom entrances and use only top entrances in the winter for now on. I’m thinking it over.