Fairfax County is home to an abundance of dragonflies. Naturalist Karen Sheffield conducted a study of them at Riverbend Park and discovered the park is home to more than 10% of North America's dragonfly species. The combination of natural communities, some of them rare, in the Potomac Gorge helps create perfect habitat for so many dragonflies. For example, Cobra Cubtail are there in June, and the Illinois River Chaser is there in July.
There are dragonfly fossils that are very large in comparison to today's largest, six-inch dragonfly. Fossil dragonflies had wingspans of more than two feet.
Dragonflies and damselflies are also quite common at Huntley Meadows Park. Classes on dragonflies and damselflies are available occasionally at Fairfax County nature centers.
Selections from a Riverbend Park Dragonfly Study Report: February 2005
by Karen Sheffield
Life-long predators, dragonflies spend most of their life as a larva in aquatic habitats before emerging into the winged adult insect. Many species are habitat specific and require unpolluted aquatic environments such as seeps, streams, and ponds. Dragonflies are valuable indicators of general ecosystem health. "The presence of a vigorous and diverse odonate (dragonfly and damselfly) fauna will always be a reliable indicator of the stability, health and integrity of a wetland ecosystem."¹
Riverbend Park hosts a variety of wetland and meadow habitats that attract dragonflies. Thirty-four dragonfly species have been recorded to date, of which 30% of the dragonflies are state rare or watch-listed species. Riverbend is home to more than 10% of the dragonfly species in North America.
Several great records were made this past season (2004). The Spine-crowned clubtail, a hybrid G3G4 and state rare species, had historically been recorded from only two locations along the Potomac River. For the first time in 25 years, the Spine-crowned clubtail was documented along the Potomac at Riverbend Park. This also was the first recording of it in Fairfax County.
The Midland clubtail (S1-state rare) and Ocellated darner (S3 - watch listed) were documented as well. The Cyrano darner (S3 - watch listed) breeds in Carper's Pond, a wooded pond that is formed from a seep within the park.
Five cast skins of a clubtail species have proven difficult to identify. The species is either the Elusive clubtail (G3 - globally rare, S1 - state rare) or the Russet-tipped clubtail (S3 - watch listed).
Four years of study focused on ponds, a vernal pool and a portion of the Potomac River.
Much thanks goes out to all of our volunteers and staff and to Richard Orr who has verified several challenging adult species and cast skins (exoskeletons). Volunteers: Edward Chein, Ryan Meczkowski, Naghma Malik, Lydia Lanni, Ellie Clark, Kit Sheffield, Andrea Menzo, Lynn Mobley, Riverbend Dragonfly Survey Group, Marijke Gate, Jamie Fish, John Callow.
¹Corbet, P.S. (1999) Dragonflies: Behavior and Ecology of Odonata, p204.