Pocantico Hills, Westchester County, New York, USA August 21, 2016 Size: 1/6" - 4 mm est.
Is this Hylaeus leptocephalus? The bee has a narrow face, and the yellow markings on its face and the front rim of its thorax seem to match those of the Hylaeus leptocephalus on the Discover Life Database. http://www.discoverlife.org/20/q?search=Hylaeus+leptocephalus (H. mesillae looks similar but lacks the thorax markings.)