Open Mesh Floors (OMFs) are floors with a variety of designs, but all of which provide a bee-tight, epoxy-coated, metal-mesh screen below the frames, in place of a wooden surface. Detritus from the colony can fall right through the floor and onto the surface on which the hive is placed. They have been used on a number of hives at Blackhorse, including the Long Hive. Very early trials of the principle were carried out locally at Merrist Wood in the 1970s. While they may not suit all climates, in our damp, mild winters they appear to persuade the bees to cluster better, fly less, and be more frugal with their stores. It is hard to disbelieve all the anecdotal evidence from many countries that they reduce the incidence of nosema, chalkbrood, wax moths, and EFB too. Recently they are being promoted again as a valuable part of an Integrated Pest Management (IPM) strategy aimed at reducing the impact of a varroa infestation, and used all year round. If you plan to introduce an open floor do so in the summer, so that the colony can acclimatise before the winter. Possible negative effects to look out for, but which we haven't noticed, include heightened attempts at robbing in the apiary, and, consequently, an increase in the number of guard bees. Interestingly, the bees don't seem concerned that robbers will come through the floor, and so don't defend it, but during a dearth they may investigate a neighbouring hive more intensively if the floor is open and more 'odourous'. If this proves to be so, use the floor as an over-wintering tool alone. And let us know!