Here’s a demonstration of how I keep shrews and mice out of my hives over the winter. Check out my shrews category for more info on shrews.
Here’s a little math for you: A typical pygmy shrew weights 3 grams and needs to eat 125% of its body weight a day to stay alive over the winter. That’s 3.75 grams per day or 125.5 grams per month (gpm). A typical honey bee (b) weighs 1 gram. So…
112.5 gpm x 10 b = 1,125 honey bees eaten per month. A typical Newfoundland winter is at about 5 months. So…
Winter → 5 x 1,225 = 5,625 honey bees eaten by a shrew per winter (assuming only 1 shrew per hive). Two shrews getting in the hive every day = 11,250 dead bees over 5 months. Three shrews getting in the hive every day = 16,875 dead bees. A rodent inside the hive, whether the bees are being preyed upon or not, stresses the bees, their immune system and their natural defensive instincts. Getting picked off one at a time doesn’t make it any better. It’s easy to see how 2 or 3 shrews per hive can do some serious damage over the winter.
Again, just look over my previous posts about shrews and you’ll see what I’m talking about.
Overlooked: The timing of this is kind of tricky. In the video, I mention how it’s better to put the mesh on during a warm day when the bees are active and rodents are unlikely to be inside the hive and get trapped inside by the mesh. That sounds great in theory, but in practice, it doesn’t often work out that way. I usually end up putting the mesh on when it’s cold and then I check the hives with a flashlight to see if there are any signs of a mouse inside.
The mesh easily knocks pollen off the bees’ legs. I used to worry about this, but I don’t anymore. Some pollen gets knocked off, but most of it seems to stick to the bees.
Finally, we’ve got those drones. Most of the drones are normally pestered out of the hives by the end of October, but not always. Often when I put the mesh on in October, it clogs up with dead drones within a day. These are usually drones that got pestered to death or froze, and then the worker bees have a hell of a time trying to drag the dead drones through the mesh. Drones can squeeze through the mesh when they’re alive (with difficulty), but it’s a different story when they’re dead. When drones start piling up around the mesh, I take the mesh off and wait another week.
So putting on the mesh isn’t an exact science. I just put it on and then see what happens and adjust accordingly, though I’m thinking I might wait until December for now on when I know the bees are absolutely clustered inside for the winter. I’ll just have to be careful not to lock in any mice (which I’ve done before and it’s not good).
March 6th, 2021: It didn’t take me long to have second thoughts about this. I have mixed results with bottom entrances that are reduced in the winter. I know a lot of people who do it. Maybe their climate is slightly different than mine. But I’ve noticed a greater build up of condensation in my hives that have reduced entrances. I wide open entrance seems like it would freeze the bees, especially on windy days, but I’ve seen the bees clustering off the bottom bars of the bottom box right next to the wide open entrance with no issues. It seems like my bees can handle the blast of cold the comes in from the bottom entrance. The extra ventilation from the wide open entrance may be more beneficial to the bees the reduced cold wind.