Hive Swarmed Today

One of my hives swarmed today around 11:00.  I watched them pour out of the hive and form a cloud of cycloning bees.  They settled in the ancient walnut next to the driveway about 60 feet up.  I did put out small 4 frame nuk box with some frames of old comb, a bit of honey and a few drops of lemon oil then ignored it for most of the day.  Around 4:00 I looked out and the sky was full of bees and within 2 minutes they were gone.  I think I caught the end of their movement.  I walked a quick circle about 100 feet from the tree but no sign of them.  The nuk box was of a lot of interest to some other bees but I guess not enough to the new queen.