Variable Bluet (Coenagrion pulchellum)
• Scientific name: Coenagrion pulchellum (Vander Linden, 1825)
• English name: Variable Bluet
• German name: Fledermaus-Azurjungfer
• French name: Agrion joli
• Dutch name: Variabele waterjuffer
• Swedish name: Mörk lyrflickslända
• Norwegian name: Variabel blåvannymfe
• Finnish name: Sirotytönkorento
• Danish name: Flagermus-vandnymfe
• Italian name: Azzurrina variabile
• Czech name: šidélko širokoskvrnné
• Slovenian name: Suhljati škratec
• Bulgarian name: Ивичесто пъстриче
• Typical length: 34-38 mm
• Hindwing: 16-23 mm
As its name suggests, the Variable Bluet is a black-and-blue damselfly whose markings are subject to considerable variation. Like in its twin species the Azure Bluet (Coenagrion puella), females may be either of the green or the blue form. In terms of body build, too, the Variable Bluet is quite similar to the Azure Bluet. And even in terms of their distribution, the Variable and Azure Bluets are quite similar, even though the former is very much the rarer of the two species in the South of Europe. In its most typical form, the male Coenagrion pulchellum has a Y-shaped mark on its second abdominal segment (as opposed to the U-shaped mark in C. puella) and its narrow blue antehumeral stripes are heavily constricted or even interrupted so that effectively they resemble an exclamation mark. By contrast, in puella the antehumeral stripe is uninterrupted. But even so the two species may be difficult to tell apart in the field without a close-up view of the male's appendages (more widely separated in C. puella) and the female's pronotum (more deeply incised in C. pulchellum)
Note: while a typical male C. puchellum may be fairly easy to distinguish from a typical male C. puella, atypical males of the two species may be quite tricky to tell apart. In that case it's often useful to look at the amount of black dorsally on S3, S4 and S5.
- In male C. puella the amount of dorsal black is often a constant 20% or so of the total lengths of S3, S4 and S5.
- In male C. pulchellum this amount of black tends to increase, with a minimum of about 20% on S3 to 25% on S4 to 30% on S5.
- Thus, if the amount of black dorsally on S3 is equal to that on S5, then the animal is likely to be C. puella.
- If, by contrast, the amount of black on S3 is clearly less than that on S5, then the animal is likely to be C. pulchellum.