I overwintered for the first time. I thought the hive had come through healthy but on closer inspection I found a lot of dead bees and this “dust” coating a lot of the dead bees and in some of the cells. I did find some mites, but this dust doesn’t match with descriptions I have read of varroa. Any insight is appreciated. I will post some more pictures below.
Looks more like wax moth than varroa to me. Doesn’t mean you don’t have varroa, but the varroa crystals are normally a small clump of white stuff in the top of the cells. Those yellow granular bits on the capped cells look like wax moth deposits, and some of the whiter stuff at the bottoms of the frames may just be mold. Looks like you have some old dead brood in there too. Do you have a local bee inspector that you could ask? My city has one who will come out for free.
Good luck, and sorry for your loss. 
Dawn
The white crystals in the cells might be varroa faeces.
Have you any capped brood with punctured cappings evident?
There might be wax moth too
How are the bees?
Dee,
I don’t think I have any capped brood. The bees are much diminished from when I started them overwintering. I’d say about 2/3 of the hive is gone.I thought I had prepared them well for overwintering. I did a quick check when I put them back out in the hard and then a more thorough check this weekend which is when I saw how bad the situation was.
Almost certain its parasitic mite syndrome. The wax moth may have just crept into a poorly defended hive.
Is it anything like this description ?
https://beeinformed.org/2016/03/08/why-did-my-honey-bees-die/
It’s a real bummer.
I’ve been caught out by late varroa onslaught. Don’t beat yourself up about it. Monitor more carefully more regularly and treat more often?
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The crumbly stuff on the outside is wax moths. The white in the cells is hard to tell. It could be crystals of honey or Varroa feces.
Here are some better pictures of Varroa feces:
http://www.justkiddinfarm.com/varroa/varroa.html
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Dee,
This looks exactly like my hive. Thank you sop much for sharing.
The good news is that after you have popped the brood frames into the freezer to kill any lurking wax moth you can re-use the combs
Thank you Michael. I appreciate your help.