Michael, you are such a great source of information.
I looked up the washboard dance: http://entomology.ucdavis.edu/faculty/mussen/03-04-03.pdf
and I feel reassured that THAT is what my bees are doing. I've been so worried because there are so many of them outside the hive while I have an empty super, SBB, and the top propped open.....but why was I worrying?
They are DANCING!!!
Linda T in Atlanta