what is this?

Sorry for the vague thread title. I'm new here. I've had bees for one year. I know what to expect when things go right but don't know much about pests and parasites and how to diagnose when things go wrong. I need more time to look through all the good threads here which will be very informative, but in the meantime I was hoping to get a quick answer on my question. But a little backstory first.

I got the hive last year and put the in the bees in mid May. They did great for 2-3 months. By that I mean it looked like the colony numbers were increasing, the comb was being built up, and pollin and honey was being stored. Then I noticed it seemed like the colony wasn't increasing in numbers and honey production started to level off. Over the next 2 months I watched the colony slowly decrease and then eventually die. The queen was always there, I made a point to make sure the queen was there and that she had larva. I'm not sure how to quantify how much larva there was, but the queen was there and she was still laying eggs. But eventually I looked in the hive and there was the queen and maybe 20 bees around her and the next time I looked a few days later all was gone. And they had eaten all the honey they had produced in past few months as well. So my noob impression is that this was a slow die out, not a colony collapse type of thing but I don't why that happened.

So I took the hive down and put in my basement for the winter. I'm just now checking on it and getting ready for this next season and something has decided to make its home in my basement hive. There's a lot of spider-web feeling tunnels through the wax in the frames and these web tunnels going from frame to frame. So that's my first question. What is making all these tunnels through my frames and wax?

After closer inspection there's a lot of little capsules that were pushed out of the comb. I think it's little bundles of pollen but I'm not sure. It's my first year with a hive, I'm sure what pollen looks like after drying out in a basement for the winter. But I had the thought that maybe it's varroa mite larva, but I'd think that would be much much smaller. But I don't know.

So I have a few pictures of this mess but I need to know if this is something that the bees will clean out when I toss them in or if I should burn the frames because it's something more serious.

So here's a pic of what I think is just dried out pollen but not sure.

And here's a pic of some of the weird tunnel stuff I saw going on.

Any help or insight is much appreciated!

cheers
matt