Yesterday afternoon while watching both hives I heard an odd sound from one. The sound of an insect chewing wood is what it reminded me of. There were bees 'walking the line' along the entrance (reducer still in on the largest opening). They were doing their cleaning thing it appeared. I didn't see any bumble type bees making a hole anywhere so I dismissed that. I wouldn't have thought they would make this much noise. Just curious more than worried. Any ideas?