The last time I really got in it was about the third week of November. I was surprised at what I thought was a large amount of capped brood. This is my first season so I have nothing to compare it to, but it was about 80% of what it was in the summer. I opened the top briefly the first week of December to remove a top feeder which they were ignoring. After that we had that stretch of crazy cold weather, then they were dead.
There's plenty of empty space in the brood box frames. I've never treated for mites, since I've never had more than 7 per 300 on an alcohol wash. Last one of those was in mid November.
I can post pictures of the frames later, maybe that will help. I'm hoping to learn something from this. Thank you for taking the time to reply.