It is rather easy to work out why the buddleia is referred to as the butterfly bush. I have one planted just outside the kitchen window and I have just counted over forty red admirals latched on to the dense panicles, sipping at the sweet nectar in the heat being reflected off the wall of the house.
Although there are quite a few cabbage white butterflies fluttering about the garden they don't appear to find the scent of the buddleia bush as seductive as the red admirals do. A pity really. If they did then I might not have the task of checking the underside of the leaves of the various brassicas in the vegetable patch for their rapacious caterpillars.