I need a second opinion on this issue. I was visiting a fellow beekeeper in my county and talking to him about winter preparations. He said that he has solid bottom boards on all his hives. When I told him I was going to overwinter my bees with a screened bottom board, he said that it would create too much of a cold draft, and that for winter I should switch to a solid bottom board. (BTW: We are located in Wisconsin, so seriously cold winter days can be expected). On one hand, I am inclined to follow this man's advice, since he has been keeping bees a lot longer than I have been alive. But on the other hand, I have some doubts about solid bottom boards because: a) I have heard several times that air moving through the hive is a good thing, because otherwise the steam from the bees gets trapped, condenses on the inner cover and drips back down on the bees. b) I have also heard repeatedly that bees don't need to keep the entire air volume of the hive warm, just their cluster. Therefore, insulation and lack of drafts is not as big an issue as lack of ventilation (see above). c) Since warm air rises, the air below the cluster will be equally cold, solid bottom board or not. So, I'd like to take a poll on this issue - do you overwinter your bees with a screened or a solid bottom board, and what works better for you? Thanks.