Mazarine Blue (Cyaniris semiargus)

Mazarine Blue (Cyaniris semiargus)
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🦋 Mazarine Blue (Cyaniris semiargus) – Overview

The Mazarine Blue is a charming butterfly in the Lycaenidae family (blues), known for the deep violet-blue coloration of its males and a subtle elegance in both sexes. Once widespread across Europe and temperate Asia, it has declined in parts of its range due to habitat loss, but it remains locally common in flower-rich meadows and pastures.


🔍 Identification

FeatureMaleFemale
Wingspan28–34 mmSame
UppersideUniform deep blue with narrow black margin, no orange or white markingsDark brown, sometimes with faint bluish shading
UndersidePale grey with small black dots and no orangeSimilar to male
FringesWhite, clearly visibleSame

Unlike many other “blues,” C. semiargus has no orange markings (lunules) on the underside, making it easier to distinguish from species like the Common Blue (Polyommatus icarus).


🌿 Habitat

  • Prefers:
    • Flower-rich meadows
    • Alpine pastures
    • Woodland clearings
    • Calcareous grasslands
  • Typically found between lowland valleys to montane regions (up to 2,000 m in southern Europe).

🐛 Host Plants (Larval Food)

Caterpillars primarily feed on clover species, especially:

  • Trifolium pratense (Red Clover)
  • Trifolium repens (White Clover)
  • Occasionally other Fabaceae (legumes)

🔁 Life Cycle

StageTiming (Europe, varies by region)
EggLaid singly on host plant leaves or flowers
LarvaPale green, slug-like, blends in with foliage
PupaFormed on the ground or low vegetation
AdultMay to July (1 generation per year)
  • Some populations in warmer climates may have a partial second generation.
  • Larvae sometimes tended by ants for protection in a mild myrmecophilous relationship.
See also  European peacock (Inachis io)

🧠 Interesting Facts

  • Named after the deep blue pigment once used to dye Mazarine cloaks worn by Cardinal Mazarin.
  • Males often bask with wings open, while females are more secretive and rest with wings closed.
  • Sensitive to agricultural intensification and meadow drainage; a key bioindicator of traditional hay meadow health.

🌍 Distribution

  • Found throughout:
    • Most of Europe (but rare or extinct in some western/northern areas like the UK and parts of Scandinavia)
    • Central Asia
    • Russia and Siberia
  • Declining in western Europe due to habitat fragmentation.

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