Success in Season 3!

Had a great harvest this year, 1st one with my Flow hive. Took 3 years but worth the wait and the angst ! 13 liters of very light flowery tasting honey.

Question : After getting the colony ready for winter i added several cups of granulated suger as back up to their 10 frames of honey. The last few weeks here in southern Ontario have been VERY unseasonably warm so the bees have been very active. What i have noticed though is they are constantly removing the sugar from the hive, flying out with mouthfuls of sugar and dropping it outside the hive. I’ve used sugar in the past without issues.
Has anyone any idea why they would do tbis???
Thanks for any insite

Did you add sugar with the honey super on? Are you sure you are not harvesting sugar syrup?