FWIW, I have found the Beltsville Insert to be better than a full screened bottomboard during cold and windy winter months. I keep hives on parallel 4X4X8's and 12's over half sized solid concrete blocks. I lost several full five frame splits with a sixth frame of pollen and a seventh of honey in hives with screened bottom boards due to the cold windy weather of last March and April. Hives in the same configuration with solid bottomboards and Beltsville inserts were not lost; lesson learned! Chuck Norton Norton's Nut & Honey Farm Reidsville, NC :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::