New York Natural Heritage Program
Blackwater Bluet
Enallagma weewa Byers, 1927
Insects

Identifying Characteristics [-]
New York has 23 species in the genus Enallagma (White et al. 2010). However, most Bluets have more blue on their bodies than the Blackwater Bluet. Adult males are mostly black on the head, thorax, and abdomen except for a pale gray color on the sides of the thorax and a blue abdominal segment nine (Lam 2004). Females and immature males have a black head with a narrow blue band behind the eyes. The thorax has a brown mid-dorsal stripe, with blue, brown, and black shoulder stripes, and pale blue below. The abdomen is dark above, pale blue below, but abdominal segment 10 and most of nine are blue (Lam 2004).

Characters Most Useful for Identification [-]
Males have dark bodies with a blue tip on abdominal segment nine (Lam 2004).

Best Life Stage for Proper Identification [-]
Adult.

Diet [-]
Damselfly larvae and adults are predatory, preying on relatively smaller invertebrates.
Blackwater Bluet Images
click to enlarge
The Best Time to See
In New York, adult Enallagma weewa have been documented from July through the first half of August (Donnelly 1999, White et al. 2010). New Jersey flight dates range from the first part of June through mid-September (Bangma & Barlow 2010).
J F M A M J J A S O N D
Present Reproducing
The time of year you would expect to find Blackwater Bluet present (blue shading) and reproducing (orange shading) in New York.
Similar Species
  • Stream Bluet (Enallagma exsulans)
    Female Stream Bluets are very similar in appearance to Blackwater Bluets, but pale areas are green rather than the blue of the Blackwater Bluet (Lam 2004). Male Stream Bluets have terminal appendages of similar shape, but differ remarkably in coloration to Blackwater Bluets (Westfall & May 1996).
  • Turquoise Bluet (Enallagma divagans)
    Female Turquoise Bluets have wider blue and narrower dark shoulder stripes and more blue on their abdominal segments eight and nine than do Blackwater Bluets (Lam 2004).
  • Blue-Tipped Dancer (Argia tibialis)
    Blue-tipped Dancer males are stockier than Blackwater Bluets and their abdominal segments nine and 10 are blue (Lam 2004). Blue-tipped Dancers have not been documented on Long Island (White et al. 2010).