As a newbie hobby beekeeper, I was devastated two years ago when I opened the hives for the first time in the spring. I found the bottom boards of both my hives covered with dead bees. There was lots of honey stored - I still have about a gallon of the stuff- so lack of food wasn't the problem. More research into winter hive preparation led me to add more ventilation and more insulation to my hives.
The first thing I did was to cut foam insulation board to fit the top of each hive. This insulates the outer cover so that warm air doesn't condense on the inside and rain back down on the hive.
Insulated outer cover
Ventilating warm air is a must during the winter months. So I added a ventilation box to the top of each hive. They can be seen ventilating on my previous post Bee Cluster: Colonies Viewed in Infrared.
To complete my winter hive insulation project, I wrapped each hive with an Easy-On Hive cover. The covers are made of foam board covered in a tough vinyl.
As a "before" picture, here is an infrared photo of the bees clustering in the lower brood box of one of my hives.
These boxes are made of ¾ inch pine and with no insulation in place, you can see the colony right through the wood.
And the "after" pictures: infrared on the left, normal light on the right.
On a sunny day the insulation can get rather toasty! Here there are hot spots over 80 °F. The air temperature was in the 40's (°F) that day.
A cloudy morning following freezing overnight temperatures was the best time to take this final photo. The ground temperature is 42 °F at the most and the hive cover is cold.
Insulated brood box in infrared.
I can no longer see the cluster. The hive is all tucked in for the winter!