Thanks to good advise, much of which came from BEE-L, and to locations with
lots of eucalyptus and wild flowers, I've already taken off 3 shallow
supers this year from some of the strong hives. I've never seen anything
like this in my life, and I think it's due to re-queening, checkmite,
medicated grease patties in the fall, and the fact that the bees don't have
any competition anymore. In our area of the California coast, there simply
are no more ferral bees.