Old hive decreasing population

Over the past 1-2 weeks, I've noticed that the activity at the entrance of the old hive seems to have diminished.  It certainly is less active than at the new hive next door.  Yesterday I took a look into the old hive to see if I could spot anything amiss.
There was no honey at all in the top super, so I decided to take it off altogether.  Only two frames in the other super had honey.
In the upper brood box, there were 4-5 frames with honey, no brood. On a few frames, there were some empty cells surrounded by honey, suggesting that brood had once been there.  There was nectar in many of the empty cells.  (So they weren't really empty, were they?)
In the deep box, there was only one small patch of brood and larvae and I didn't spot the queen.
I did get the sense that the population had contracted.  Previously, there had been bees in the Vivaldi box, but there were no bees above the first super on last inspection or this one.  Also, there didn't seem to be as many bees as previously in the upper brood box.  Once again, we'll have to wait and see.

Pieces of propolis

On the bottom of two adjacent frames were leafs of propolis.  It looked like they may have formed a small dome.  I looked in the hive to see if there was anything the bees may have walled off, but I saw no foreign objects.  I took the propolis and added it to my small collection. 

Bees in jar coated with powdered sugar

Only two!

I did another sugar roll count.  This time I changed my collection technique.  I used a larger mason jar, put the powdered sugar in first and used a measuring cup to scoop the bees out of the bucket.  It was much easier, I got the full 1/2 cup and I didn't squish anyone.  This time there were only two mites- hooray!