For some reason open mesh floors on newly made up nucs just don't seem right to me..i hate looking down at day light when inspections are being done ..also i suspect wasps and robbing bees hawk around underneath more as the smell from inside the nucs will be stronger through the mesh floor..my remedy for this like i did with my paynes poly nucs is to make inspection boards out of for sale signs and strap them firmly to the underside of the nuc's..to me this gives the bees a more natural dark chamber with the option of removing the inspection board during mite treatment.