this has come up before.........these 'gates' appear to be made similar to mouse guards. unless somewhat larger, the mouse guards will strip pollen off the legs/pollen baskets of the bees. i wouldn't use these for mite treatment. bees will still be bringing in pollen late in the season from whatever is available, and during times for fall treatment for many of us that treat bees for mites. i would find a different method of mite treatment. just my HO.