Marlton, Burlington County, New Jersey, USA September 17, 2007 Size: Maybe around 10 mm?
I believe this may be "Boomerang Eucosma Moth" -- Eucosma similiana. The guide page seems to say that Eucosma similiana and Eucosma diffusana are collapsed into one species on BugGuide, but in September it seems they were split again. http://bugguide.net/node/view/145494/bgpage http://bugguide.net/node/view/80200