The Variable Damselfly is easy to confuse with other damselfly species
The Variable Damselfly is a known as a Coenagrion or ‘Blue’ damselfly, a group of closely related blue-black species which are strikingly similar in appearance. The two most common Coenagrion in the UK, the Azure Damselfly and Common Blue Damselfly, are easily confused with the Variable and all three can be found in the same habitat, making reliable identification a must.
There are a number of features used to separate the species from its very similar cousins. To start with, rule out the Common Blue Damselfly by looking at the side of the thorax (the body where the legs are located). All other Coenagrions feature a short black line on the side of the thorax (the ‘Coenagrion spur’); whereas the Common Blue does not, instead showing an all blue side to the thorax (‘Common Blue is All Blue’).
Next, we use a group of features to identify the Variable Damselfly males from the other Coenagrions. Look out for the incomplete shoulder stripes on the thorax (‘the vampire’s dripping fangs’) and the distinctive goblet shaped black mark at the top of the thorax, on segment 2 (depicting a goblet used to catch the dripping blood!). Also look out for a small blue line between the eyes (the post-ocular bar) on the Variable Damselfly, which is lacking on the Azure Damselfly. Finally, the shape of the pronotum (a body part directly behind the head), the Variable Damselfly has a distinctly lobed-shaped pronotum. But beware, the Variable Damselfly is variable, so look for the combination of features rather than relying on one feature alone. Female Coenagrions are so similar it is advised that only those with experience in differentiating them do so.
The Variable Damselfly is found in and around well vegetated ditches, canals and ponds, rarely in flowing water habitats.
Distribution and threats
The Variable Damselfly is currently listed as Near Threatened in the Red Data Book for Great Britain. It is scattered but uncommon across mainland Britain, with hotspots at sites such as the Ouse Washes and Somerset Levels. Over the last 20 years records for the Variable Damselfly have declined. This suggests a contraction in the species’ range, with implications for its conservation status.