I’ve noticed that bees like wisteria.

And cornflowers.
 Ajuga too, especially at dusk.
And lupins and iris.
All of which makes me think…
Bees like purpley blue stuff.

(although I have no photographic proof, not that I didn’t try—flighty buggers, bees—so don’t strain your eyeballs, there’s no buzzing in those blooms.)