Length of Northern Bluet: 29-40 mm
Length of Boreal Bluet: 28-36 mm
These two species are so similar most of us will be content to label our specimens or photos "Enallagma cyathigerum/boreale." Even an in-hand examination of the cerci of the two species can prove tricky, as the cerci are very similar.
Some of the traits shared by Northern and Boreal Bluets are large eyespots, and a mushroom-shaped black spot on abdominal segment S2 (seen dorsally).
Females are blue or olive, but in either case will have a tapering black shoulder stripe, wider at the bottom and narrow at the top near the wing bases.
Both Enallagma boreale and Enallagma cyathigerum are early season species, active in West Virginia from May through mid-July. They may be found living at ponds, lakes, bogs, and marshes, though not usually at streams.