The Southern Damselfly (Coenagrion mercuriale) is one of at least four blue damselflies with black markings that seem similar at a quick glance. The others include the:
– Common Blue Damselfly (male has a domed mushroom-like black mark on abdominal segment two)
– Azure Blue Damselfly (fine “U” shaped mark which has no stem on abdominal segment two)
– Variable Damselfly (wine glass or “U” shaped mark on abdominal segment two with a stem at its base)
The second abdominal segments bear the most distinctive markings that help in the identification of the different species.
Like its specific name suggests, the Southern Damselfly spots a distinctive marking on the second abdominal segment that resembles the astrological symbol for the planet Mercury (☿). It’s alternative name “Mercury Bluet” is therefore more fitting and descriptive.
Other identification characteristics include:
– Elliptical spots behind the eyes
– Blue bar between the eyes
– Abdominal segment 9 is 80% black
To the untrained eye, these species all appear the same. But it can be even more fun looking out for these unique markings that give the different species the identification they possess