I have the same concerns with my concertina, but fortunately, the reed pan is enclosed and I don't think a fly could get in there. I remember the first time a reed got stuck (it's only happened twice). I was afraid to open the instrument up for fear I'd ruin something. But I did open it, and just gently popped the stuck reed open. Simple.

Margo

(At least the fly wasn't doing the breaststroke)