Are we all using them?  Anyway, what to do with them during the winter?  It's the opinion of many that the board should not be blocked, allowing the air circulation in the hive. An interesting article in September’s Bee Culture discusses completely open bottom boards (OBB’s). This is a hive design where there is no landing board and the entire bottom of the lowest box is left open and fitted with half inch hardware cloth screen. The article is too long to fairly summarize here but it makes interesting reading. Page 44 - and you can also try googling for COBB, “open bottom board”, or “commercial open botom board”.