It's not honeycomb in the ordinary sense, so no honey. Mason bees are simply looking for somewhere to lay there eggs. They will find what looks lkke a suitable hole, or in some cases, make one in soft masonry, they then lay the egg, leave some food - more likely pollen than honey, for the developing grub. Many will then seal off the egg chamber with a mud plug and then lay another egg ansd seal it off and so on. The following spring, the adult bees formed from the eggs bite their way out , starting with the last to be laid, and fly off to start the cycle again. I have the same problem with drainage holes in double glazing. The best solution is to temporarily block off the entry points with something like insulating tape so that they fly off and find more suitable nesting site. Mason bees, of which there are quite a few species are solitary bees with varying nesting habits. They are valuable polinators so it is good to encourage them; but not in glazing!
Jim
