Hello Gang, I placed Open Mesh Bottom Boards (OMBB) under all my hives a few weeks ago. The chalk brood is nowhere to be seen. I noticed that some bee parts were partially pushed through the screed (8 mesh). The bees were from winter kill that were sticking out of cells. I did not see any chalk, but will place a sticky paper under the mesh to see what is getting through the mesh when the weather finally warms up. There was a lot of chalk before I placed the OMBB. A hole in each super, (3/4 inch) provided better ventilation during the winter, so there was very little black fungus growing on the solid bottom boards and corners of the brood box where it usually does. I suspect the air flow has a lot to do with this. I further suspect that the OMBB provide added air flow to clear up the chalk. I plan to keep OMBB on all winter. I will report the findings here at that time. The OMBB are much cleaner than the normal solid bottom boards usually are. My design allows the screen to be removed from the back without lifting the hive off the OMBB. It simply is removed like a drawer to a pollen trap. Ernie Gregoire "Beekeeper," definition= partially brave, partially excentric Grist Mill Apiary Canaan, New Hampshire, USA ------------------------------------- 04/27/99 13:54:53