Robert Brenchley <[log in to unmask] wrote:
"Is this a trait of American bees, that they need sun while British ones
don't, or what? It would make sense if ours were adapted for shade, given
our weather, but has anyone ever looked into it?"

I don't know whether any one has looked into it but from my own personal
experience I do notice that I bees I keep in an apiary which is shaded from
noon onwards tend to be more easily set into defensive mode than the hives I
keep in an attached but  non shaded apiary.  The bees in the shaded apiary
also settle down and stop flying earlier in the evening than the other
colonies and particularly seem to resent being disturbed within 2 hours of
sunset.