One of my clients had used a hive top feeder that holds a ton of syrup. After the bees stopped taking any, he continued to leave the feeder on, and full "just in case." A few weeks later he called to tell me that his hive was very weak, and in fact he was not sure there were any bees in there. To be clear, I had seen the hive several weeks after the package install and they were doing famously.
So, will rotting or fermented syrup weaken or even kill a colony? Sounds like there is an obvious answer, however I would think if the syrup was fouled the bees would just stay away from it.
Jeff.
Reading between the lines, I would guess the new package superceded and the new queen didn't make it. When they became queenless, they quit taking the syrup. That's when he should have checked it and didn't. I don't think they would take syrup that would hurt them.
What Wally says is about right on. New packages will often supersede their queens. Swarms often supersede as well.
...JP
Thanks fellas. Always something new to learn.