Pearl Crescent, first sighted of season, Thursday, May 23, 2013, on Anthony Waterer Spirea (kept coming back to this one plant).
Seems early for this species here. I usually associate Pearl Crescents in my yard with August and composite flowers in blossom.
http://www.flickr.com/photos/30318416@N03/8793578975
http://www.flickr.com/photos/30318416@N03/8793581039
Larry Barry, Harwich