Here's how to put together an insulated inner cover for your beehive without having to buy a new cover or build one. I learned this method from Phillipe at MudSongs.org , he has some great info on his beekeeping site, very down to earth.
An insulated inner cover reduces or prevents condensation in the beehive in winter.
Why does this matter? Condensation is water that collects on the top of the hive. It forms on the side of the inner cover that faces the bees. When enough water collects, it will drip back down onto the bees. Not a good thing.
Wet bees are dead bees.
Especially in winter.
How does this cover help? Condensation happens when warm air meets a cold object. In the beehive in winter, the bee cluster is warm, and there is some humidity in the air. When the warm air from the cluster rises and hits the cold inner cover, the water vapor condenses and drops back onto the bees. Not good.
The insulation that sits on top of the inner cover here keeps the cover from getting real cold, thus reducing or eliminating condensation. Since I have been using the insulated inner cover, I have not seen signs of condensation in the hive. If you find mold in your hives, you have condensation, FYI.
My variation on the insulated cover is to put a shim between the upper super and the inner cover. I then put sugar on top of the frames, using the dry sugar, aka mountain camp, method. This sugar provides a backup food source, and absorbs moisture in the hive.
Be sure the slot of the inner cover is not covered, one should always provide an upper entrance to the hive, plus it allows for air flow. Yes even in cold weather, I believe a hive needs some air flow, so provide an upper entrance. Remember to invert the inner cover.
You should also insulate the sides of the hive.
- Outer cover sits on top of insulation, and usually covers it.
- Insulation - I use 2" thick polystyrene.
- Inner cover, turned upside down, flat side faces upward.
- Spacer shim, with dry sugar on top of newspaper.
- Top brood super
I built some DIY insulated inner covers that are more involved than this stack method, and they work well for me. If you are handy, have at them.