New beekeeper. took delivery of bees on april 5 and things went great. population grew dramatically, brood box has comb on every frame and the bees seemed to be overflowing with bees hanging out on the outside of the hive. Added the flow super around May 27. Bees immediately started working in the flow frames and seemed happy. Yesterday noticed that the flow super was completely empty. It seems all the bees that had populated the flow super are gone. The population in the brood box is still good, but its down dramatically from May 27.
open to any ideas.