The swamp spreadwing varies from 1.7 to 2.2 inches in its length. The male's thorax is metallic green above with thin brown shoulder stripes and pale yellow sides. The abdomen is bronzy green above with a pale gray tip at maturity. The colors are obscured by pruinosity as the spreadwings age, especially in males. The male is usually elongated with the female more sturdy. The female's thorax is green above with brown shoulder stripes and gray-yellow sides. The abdomen is green above and dull brown below. Both sexes could be confused with the elegant spreadwing in the field but the swamp spreadwing is smaller and the green coloration is duller.
Ranging throughout eastern United States, this species is usually found at vegetated ponds, marshes, stream backwaters, and boggy lakes. In Wisconsin, it is locally common and widely distributed throughout the state.
Late May to late September in Wisconsin.