In the winter, people make a big deal about sealing up their hives. “The bees will freeze!” is often the battle cry. “You don’t know how cold it get’s on my property” is another one. As much as I hear this, I just have to smile. Like the old weather adage says, “it’s not the heat, it’s the humidity” silly!
An experienced beek will tell you, bees almost never freeze to death in a hive. Bees are amazingly good at keeping the queen and her eggs an impressive 94F, even when temperatures outside the hive are sub-zero for weeks at a time. However, the one thing they can’t tolerate is moisture which is another way of saying very high humidity.
Bees, just like any other animal, breath out warm, humid air. But unlike other animals, bees do it packed together, in an enclosed space. Not having enough ventilation in the hive simply to let out the humidity causes it to build up and condense on the inner cover as water. As it condenses, it forms drops of water that cling to the inner cover, randomly dropping onto the colony like bombs from an air raid, killing bees with each drop. Since the humidity can’t escape, more water drops form from the bees’ breath, and the cycle continues until the hive is decimated. Death from your own breath – what a way to go.
The only way to avoid humidity build up, besides asking the bees not to breath in the hive, is to allow the humidity to escape. Since human-built Langstroth hives often have an entrance on the bottom, holes are usually used towards the top of the hive to allow the humidity to escape. This occurs because of the “chimney” method which allows air to flow in through the bottom of the hive, be heated by the inside of the hive, and want to rise out the top of the hive, thus carrying the humidity out with it. And a dry hive is a happy hive. Well, OK, a dry, well fed hive with a laying queen and attentive workers is a happy hive. But I digress…
So all the fuss about sealing up your hive, wrapping it in tar paper, putting a heater underneath it; it’s all well intentioned, but misguided. If you take steps to make sure the hive is dry, the bees will keep it warm enough. Let them do what they naturally do best. Your job is simply to be a a benevolent landlord. Give them a nice place to live, and they’ll do the rest. It’s what they do; they’re bees.