Danish common name: Hjelm‐vandnymfe

Small, deep blue damselfly, typical of small streams in south-western Europe. Male’s S2 is marked with a black double-horned triangle, which has been likened to Mercury’s helmet.


Total: 27-31 mm.
Abdomen: 19-27 mm.
Hindwing: 12-21 mm.


Sunny streams and springs with rich aquatic and riparian vegetation. Flowing drainage ditches may also offer suitable habitat.

Flight Season

From mid-May to mid-August. Most abundant in June and July.

Range and Status

Not yet registered in Denmark.