As a point of interest as to why we do not let bees clean out our extracting equipment as well as open honey supers, here is good information on robbing and and how to manage the situation. Bees learn very quickly, so it's best not to get them started.
It's fall. Are you and the colony ready for winter? Here's a great article from Kelley's on "Putting Your Bees to Bed for Winter".
Northeastern Kansas Beekeepers