Males become mostly dark, with a bit of pruinosity on the lower portion of the thorax, a black abdomen with narrow basal rings on the segments and pruinose blue on S9 & 10. Usually perches on the ground, occasionally on t-shirts, as the one in the photo is doing.
Dusky Dancer is also dark, but the blue tip of the abdomen is replaced by small blue spots on S8 & 9.