I seen this in one of my hives last year at this time of year when the mites are exploding, at first I thought it was robbing but after I watched this one hive for awhile I looked at one of the bee's that got thrown out and it had deformed wings (DWV) but they would kick out a bee every couple minutes and then it would stop for awhile and a little later I would see them doing it again. after about a week it all stopped and the hive did very well, I didn't treat this hive with anything, I have never treated any of my hives with anything (lucky so for)