I have seen quite a few leaf-cutters foraging in the garden in the past couple of weeks but haven't seen any signs of leaf cutting or nest building. The flower they like best is Geranium "Johnson's Blue". I am pretty sure all the males are Megachile willughbiella. They have white hairs on their faces and on the tarsi on their front legs.
I suppose the females are probably all M. willughbiella as well but I wonder if some might be M. centuncularis.