When I saw this moth, I thought of hawk moths, and found the What's That Bug? pages whilelooking for images of them. Nope, some similarities, but nobody quite like this guy (or gal). I saw a couple of them today, and haven't seen them before AT ALL. However, we recently (cough) said enough is enough and set out self-contained ant baits, because we had ants in ANY flower, so I think we've not been on anybody's pollination route. We're seeing bees and maybe some clearwing moths too now.
The moth makes a definite flutter, a thwfffflflflfl sound which is almost on the verge of being a buzz. Didn't see it doing any hovering, a la the hummingbird moths (wow, they are cool, didn't know about them!). That's a cornflower that the moth is on, about 1.5 inches across, so that gives you an idea of the moth's size.
Really pretty little moth! Catches the eye in the garden. I hope it's not up to something nefarious. ;-)