The Sweetflag Spreadwing is unique among spreadwings in that it's easier to ID the species by looking at the female, not the male.

Photo to left:  Side view of female's ovipositor (egg-laying appendage at end of abdomen). Note that the lower part extends well beyond the upper part. This feature shows up well enough to be visible through binoculars.

The males are best identified by finding them along with (preferably attached to) the females.