Hi all

I noticed last year that the hole in the front of my bird box had been
enlarged considerably by previous occupants and thought that this was
probably the reason for the lack of recent interest.
So I made a cover plate out of aluminium with a smaller (original size)
hole.
This year I had some interest, but decided that the birds didn't use it
because their attempts to alter the access simply resulted in headaches or
bent beaks.
So I removed the aluminium cover plate with the intention of making a wooden
ply version.
This I did, but when I went up the ladder recently to fit it I noticed that
there was a nest in the box, but no feathered inhabitants.
I started to remove the lid and noticed that a loud buzzing noise started
issuing from the box!!!
Needless to say I descended the ladder rather smartly and left well alone.

So what has taken over the bird box? I have had wasp issues before and know
how they behave - haven't seen any of those.
Despite frequent glances, I have yet to see any flying insects entering or
leaving.

Anyone know-or-can-suggest the likely culprit?

Phil