I got packaged bees in April. I have an 8 frame super. I had a very thriving hive all summer. I fed them sugar water starting in the beginning of august. I went on vacation for 4 days back in the middle of October. We had our first cold snap. When I got back I saw that the bees had deficated on the front of the hive. I opened the hive slightly (it was below 45 degrees) and i noticed right away there were fewer bees. I assumed they were clustering in the brood super. I then starting seeing robber bees going in the back entrance. I tipped the hive and realized it was probably about 50 lbs lighter. I decided to go in even with the cold temps. When I took the hive apart it was completely empty of bees. A few dead ones but no bees. Here are some photos I took. Maybe someone can help me figure out this mess. I did not treat the bees with anything. Thank you.

https://picasaweb.google.com/108000792145175466212/Hive