The name "forktail" comes from tiny projections off the tip of males' abdomens, which help to identify the species. The length of the body varies from 0.8 to 1.3 inches. The eastern forktail male has a green thorax and almost entirely black abdomen with a blue tip. The female is orange with broad black mid-dorsal stripe and thin shoulder stripes. The abdomen is orange at the base and mostly black above. As the female matures, it becomes powdery-blue. Old females will be difficult to distinguish from other old female forktails.
This species is very common, ranging from eastern to central United States, including southeastern Canada. It is usually found at a variety of permanent still waters, including ponds, ditches, marsh bays, and streams. It seems to avoid acidic wetlands, i.e. bogs. In Wisconsin, it is one of our most common damselflies statewide.
This species has the longest flight season of any Wisconsin damselfly. It has been found from early April to early November. The typical flight season is early May to late September.