I also am a newbie
I have one colony that looks like it pushed half the population out the door on the coldest day or the year.
Many times more dead than any other colony I have, definately not normal. There is still a lot of bees in the colony, with plenty of honey. They are italian, and there hasn't been any drastic improvement in weather, It was at or below zero at night and mid-teens during the day for the last three weeks - although it was above freezing for a few days before that - about the last time I took a walk past them.
The only thing different about this colony is that I added a swarm to it in early September minus the unknown queen. Maybe they had Tmites?
Any ideas? If it is Treacheal mites, How do I tell - they can't be seen, can they? and what can I do about it?
Change is inevitable, Growth is optional