Blue-Tailed Damselfly

• Its one unique diagnostic feature is a strongly marked dorsal projection on the pronotum, visible with a ten-times hand lens.
• It is one of the most widespread and abundant dragonflies and damselflies in Europe, from Ireland and north-western Iberia to Japan.
• The nymphs are carnivorous and breathe through three large external gills at the end of the abdomen.
• It is one of the most abundant and adaptable damselflies in Europe, and it quickly colonises new ponds, gravel pits and irrigation reservoirs.
• Its females come in several very different colour forms, and one of them, the so-called androchrome, mimics the blue of the male. That mimicry helps her avoid sexual harassment: males mistake her for another male and leave her alone.
• It is a textbook case of polymorphism maintained by frequency-dependent selection: when one form becomes common, males learn to recognise it and its advantage disappears, which favours the others.
• It is identified by a bright blue segment near the tip of the abdomen, which stands out against the dark remainder and gives it its English name of blue-tailed.
• Its tolerance of pollution makes it of little use as a bioindicator, unlike the beautiful demoiselle.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat & environment

Fringing vegetation around bodies of water, including heavily eutrophic settings such as irrigation ponds and garden pools. The adults do not stray far from the water

Sexual maturity

One generation a year in central and northern Europe; in the south larval development is faster and there may be two

Gestation / incubation

The eggs take 2 to 4 weeks to hatch

Litter / clutch size

The female lays her eggs on floating vegetation after mating

Sources consulted: IUCN Red List; Sánchez-Guillén et al. 2011, BMC Evolutionary Biology 11; Waste Magazine (Guía de odonatos ibéricos); Animalandia (Comunidad de Madrid)

Best time: From late April to late September in central and northern Europe; in the south it may be on the wing from February to October