Here’s a full scientific and natural history overview of the Beautiful Demoiselle (Calopteryx virgo), one of Europe’s most elegant damselflies, known for its metallic shimmer and graceful flight over clear forest streams.

🩵 Beautiful Demoiselle (Calopteryx virgo)

Taxonomy

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Insecta
• Order: Odonata (Dragonflies and Damselflies)
• Family: Calopterygidae (Broad-winged damselflies)
• Genus: Calopteryx
• Species: C. virgo

General Description

The Beautiful Demoiselle is a large, broad-winged damselfly with a metallic, iridescent body that glows in sunlight. It is one of Europe’s most striking Odonates, often seen fluttering like a butterfly along forested streams and rivers.

• Body length: 45–49 mm
• Wingspan: 60–70 mm
• Male: Metallic blue or blue-green body, with deeply colored, dark blue wings.
• Female: Metallic green or bronze body, with translucent greenish-brown wings that have a white pseudostigma (spot near the tip).
• Both sexes exhibit a beautiful metallic sheen that changes hue depending on light and angle.

Distribution

The Beautiful Demoiselle is widely distributed across:

• Europe: From Ireland and Portugal eastward through Central and Northern Europe to the Balkans and the Ural Mountains.
• Asia: Extends into western Siberia, the Caucasus, and parts of the Middle East.
• Prefers temperate regions and is more common in western and northern Europe than its close relative, the Banded Demoiselle (Calopteryx splendens).

Habitat

• Found along clean, fast-flowing rivers and streams, especially those with gravel or rocky beds and wooded banks.
• Favors shaded, unpolluted watercourses in hilly or forested areas.
• Avoids still or stagnant water.
• Presence is a good indicator of high water quality.

Behavior and Ecology

• Flight period: May to September (varies with climate).
• Activity: Diurnal; males are territorial and defend stretches of streamside vegetation.
• Flight: Fluttering and butterfly-like, often hovering gracefully above the water.
• Resting: Commonly seen perched on leaves or twigs near water.
• Diet:
  • Adults feed on small flying insects, such as midges and mosquitoes.
  • Larvae (naiads) are aquatic predators, feeding on insect larvae, worms, and small crustaceans.

Reproduction

• Courtship: One of the most elaborate among damselflies:
  • The male displays his metallic body and flutters around the female in a characteristic “butterfly dance.”
  • If accepted, the pair forms the tandem position for mating.
• Egg-laying (oviposition):
  • The female inserts eggs into submerged plant stems or soft vegetation just below the water surface.
  • She often remains underwater for several minutes while doing so.
• Larval stage:
  • Lasts up to two years, depending on temperature and conditions.
  • Larvae live among submerged plants and stones, emerging in late spring or early summer to transform into adults.

Conservation Status

• IUCN Red List: 🟢 Least Concern
• Population trend: Stable across most of its range.
• Threats:
  • Water pollution, siltation, and loss of clean streams.
  • Deforestation and removal of riparian vegetation.
• Acts as a bioindicator species—its presence signals good freshwater ecosystem health.

Identification Tips

Ecological Role

• Controls populations of small flying insects.
• Serves as prey for birds, spiders, and amphibians.
• Its aquatic larvae help maintain balance in stream ecosystems by preying on smaller invertebrates.

Interesting Facts

• The metallic blue and green coloration is not due to pigment, but structural iridescence, caused by light scattering from microscopic scales.
• Males often return to the same perch or territory day after day.
• Females can remain underwater for up to an hour while laying eggs—breathing through stored air around their bodies.
• The species’ presence is often used by ecologists to monitor water quality in conservation projects.

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