On August 26 all was well with my hive upon inspection. I did a sugar roll and only found 1%. On the 30th I noticed a commotion at the hive with bees making lots of noise and flying around in front of hive. They seemed agitated. I saw a squirrel nearby and thought that was the problem. Then 9/13/17 (Wednesday ) it got hot here again and there was bearding which I hadn't seen in a while. That night the temperature went down into the 50s. The next am there were still bees outside the hives. They were just there stuck to the side of the hive not but moving. I had to go to work after that discovery but in the afternoon I noticed bees crawling on the grass not flying. Finally got in hive today and found top brood box nearly empty and bottom brood box perhaps a third full of bees. No honey. Nothing. Dead bees on screened bottom and in front of hive. I was thinking robbing because there's no honey, but maybe I should have been feeding them [I wasn't ]. Or was it a disease? Anyone care to guess? I'm new to this and feeling like I made a huge mistake somewhere along the way. I had brought sugar syrup out with me as I planned to see if they needed it. So I left them the syrup. What else can I do?