An interesting article came to me this morning about someone else noticing honey bee clustering. As most of you know, this is hard work for the bees and they use this method to keep warm.
My first installed hive, in a class, froze to death in a conventional hive. Hence, my enthusiasm for the stationary horizontal hive invented by Fyodor Lazutin. He provides the plans in his book
Keeping Bees With A Smile. I have to build this hive myself but, it's worth it. The walls are 4" thick and insulate the bees magnificently.
Honey Bee Clustering