There has been some discussions about inner covers and top ventilation on the list lately. We had the same topic here about a year ago, and will undoubtedly see more of it. It seem to be the common practice in some parts of the world to always leave a hole at the top of the hive to provide ventilation through the hive. Others state that there should only be ventilation in the bottom. I have styrofoam hives with no top vent. The entrance is 8 mm high, and there is a hole 250 by 250 mm in the center of the bottom board with a steel mesh to provide ventilation. I have been thinking of making a test one winter but never got around to do it. Last year however, a woodpecker decided it was time to check it out. Now Woody didn't seem to care much for the scientific value of his work, the shapes and sizes of his holes were a bit irregular. Most of the holes were in the upper box, some boxes had up to 3 holes. He choosed about 20 hives for the test. We had a long and cold winter here with temps down to -20 C for several months. The entrances were closed with ice for 2 months on the hives without the extra ventilation, only ventilation left was the hole in the bottom board. As dead bees fell down on the mesh during winter, the circulation of fresh air in the hives would decrease. On Woody's hives the entrance didn't freeze completely, the air flow through the hives kept it open. So, did I see any difference between the hives with extra ventilation and those without after winter? The answer is no. Both groups had wet and dry hives. And there didn't seem to be any difference in food consumption either. -- Regards P-O Gustafsson, Sweden [log in to unmask] http://www.kuai.se/~beeman/