I've put screened bottom boards on my hive for a couple of years without any sticky board. The bottom of the board is open so mites will fall to the ground a couple of feet below hypothetically unable to climb the distance back to the hive. This also improves ventillation and hasn't been a problem in the winter as I leave the hives this way all the time. My question is, has anyone done any experiements on hives set up this way and compared it to hives with sticky boards? Or does anyone know how far a mite can crawl?