Roy Page FRES who must now be well into his nineties told me that in his teaching days one of his students ( I guess in the 50s) noticed a shaking dance such as Aaron describes. From the reactions of other bees the message was "I have this itch between my shoulder blades where I can't reach. Can you scratch it for me please?" ie an invitation to groom. This was in the UK decades before varroa appeared here. Chris