This is only in one of my 2 hives. Gray splotches, hard to scrub out. Any ideas what it might be?
It looks like bee hive debris. My wife reckons to use hot soapy water.
Resin on a native bee viewing window IS hard to shift. On that she used eucalypus oil, turps, nail polish remover that is free of acetane & a lot of elbow grease.
Personally I prefer to use a solid floor, that way the bees of a strong colony will keep the floor clean.
It looks like a moldy gray color but is very hard and flakes off. Just weird looking compared to all the yellow and brown residue.
I think it’s dried up mold. I see that on my hives some times- I think it is likely pollen residue that has gone mouldy.
Mould. Dilute bleach will shift it