Agalliopsis cervina.
Size: approx. 3-4 mm. Photo: 07/23/16, 10 pm.

The second link describes a sister species: "Shaw (...) studied the sound production of an Agalliopsis species, A. novella. The male begins by emitting 'common sounds' which are unique to the species. If receptive, the female responds with the common sounds. The two then alternate producing these sounds, and eventually the male moves alongside the female. At the side of the female, the male soon attempts copulation 'by leaping onto her back.' But just before making this leap, the male emits the precopulatory sound, 'a sequence of irregular buzz-like pulses' accompanied by a vibrating of his wings."  
bug guide (this photo):
American Insects: