The citrine forktail varies from 0.8 to 1.1 inches in the body length. The name "forktail" comes from tiny projections off the tip of males' abdomens, which help to identify the species. The male's thorax is black above with yellow shoulder stripes and yellow sides. The abdomen is bright yellow with black triangles above and the tip all yellow. The stigmas, near the tip of the wings, are reddish on the forewings and brown on rear wings. The female's thorax is orange with broad black mid-dorsal stripe and thin black shoulder stripes. The abdomen is mostly orange with black markings. The last half of the abdomen is black above. When the female gets older, it becomes dark bluish gray and thus difficult to separate from other older female forktails.
Ranging from southwest to eastern United States, this species likes marshy ponds, vernal pools, stream backwaters, seeps, and wetlands. It is rare in Wisconsin, being known from just a few, widely scattered sites.
In Wisconsin, relatively few adults have been documented. Throughout its range, the flight season is from early June to late September.