Banded Demoiselle

The banded demoiselle (Calopteryx splendens) is a metallic blue-green damselfly of slow, clean rivers in Europe and Asia. The male has a dark band across each wing, and flutters like a butterfly.

🧬 Field Guide Specimen: Open Banded Demoiselle in the CRV Science Field Guide to log the specimen, see its place among the Ecdysozoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

Males defend riverside territories and perform display flights, showing off wing patches to females. The wing band is a sign of quality and condition, and females favor males with bigger or darker bands.

The larvae live in the current among plant roots, taking oxygen through three leaf-like gills at the tail end. They need clean, well-oxygenated water, so the damselfly declines with pollution and river engineering.

The body color is structural, produced by layers in the cuticle that reflect specific wavelengths, not pigments alone. See Ruby-throated Hummingbird.

• Common Blue Damselfly — a pond damselfly
• Green Drake Mayfly — another insect that needs clean water