Length: 26-33 mm
This species is highly similar to another Enallagma species, Enallagma civile (Familiar Bluet). There are other look-alike species, but in West Virginia the primary one is Enallagma civile.
The two species are so close in fact, that they should be separated by an in-hand examination of the cerci.
This site's Familiar Bluet page has more information about these two species and their preferred habitats.
Ingram and Jenner (1976) studied the life history of Enallagma hageni in the highlands of western North Carolina. They noted that this is a univoltine species that overwinters as larvae in instars F-6 to F-2. Adults reached their greatest population density on 28 June, and the last adult seen for the season was recorded on 10 August.