I have seen 2 or 3 of these......here's another image....sleeping in the forget me nots.....wasn't sure about the Knotgrass moth as that looks a lot darker in colour but have been through all id books and sites I could find and no luck. Thought it might be a moth of some sort because it isn't like any of the butterflies I see in the garden usually. Still not sure...but I left the weeding for a bit