I was checking some hives yesterday which I had requeened a couple of weeks
earlier. I had killed the queens and left the hives queenless for a day.
Then I removed three outside frames and introduced three frame nucs with
laying queens into the middle of the top box.  I found that some of the
hives had killed their new queen and are queenless.  I doubt that I would
have had any problem earlier, but the bees are in intense robbing mode.
What should I have done differently?  I would rather not have to use
newspaper and extra boxes if there was another method.  Has anyone tried
spraying the bees with light syrup?  If I had waiting two weeks I could have
made the introductions after I started feeding, but the nucs were getting
crowded in three frames.