Re: Increased Activity
I'm new too, but I'd say open the hive and try looking down and see where the bees go after leaving the feeder. If they feed and go out, then they are robbers. If they feed and go up then they are storing and they are growing nicely and harvesting. Also how fast are they going through the syrup? If they are all leaving and collecting AND feeding a jar a day, then it might be robbing.
Do you have an entrance reducer on? If you have it to the smallest setting and they are active then robbers can't really get in.
Disclaimer: I know enough to know I don't know anything yet.