Common blue (Polyommatus icarus)

Here’s a detailed overview of the Common Blue butterfly (Polyommatus icarus), one of the most widespread and recognizable blue butterflies in Europe:

🦋 Common Blue Overview

• Scientific name: Polyommatus icarus
• Common name: Common Blue
• Family: Lycaenidae (blues, coppers, and hairstreaks)
• Wingspan: 28–36 mm
• Flight style: Fast, low, fluttery — often close to grasses and flowers

🌍 Distribution and Habitat

• Range:
  • Found across Europe, North Africa, the Middle East, and temperate Asia as far east as Mongolia and Siberia.
  • Common throughout the British Isles, continental Europe, and Mediterranean islands.
• Habitat:
  • Prefers open grassy areas:
    • Meadows
    • Road verges
    • Coastal dunes
    • Heathlands
    • Brownfields and parkland
• Often thrives in flower-rich grasslands, particularly with legumes, which are important for their larvae.

🐛 Life Cycle

• Broods:
  • Up to 2 or 3 generations per year depending on latitude and altitude.
    • Southern Europe: April to October
    • Northern Europe: May to September
• Eggs:
  • Laid singly on young leaves or flower buds of host plants.
• Larval food plants:
  • Mostly legumes, especially:
    • Common bird’s-foot trefoil (Lotus corniculatus)
    • White clover (Trifolium repens)
    • Black medick (Medicago lupulina)
• Larvae:
  • Green, slug-like with short hairs
  • Sometimes tended by ants in a mutualistic relationship
• Overwintering stage:
  • As larvae in cold climates

🟦 Identification

♂ Male:

• Bright violet-blue uppersides with thin black border and white fringe
• Undersides: pale brownish-gray with black spots and a row of orange lunules along the wing edges

♀ Female:

• Variable: usually brown upperside with orange spots, but often with blue suffusion, especially in warm areas
• Underside similar to males, though sometimes darker

✅ Key difference from similar species:
The black spot near the base of the forewing underside helps separate P. icarus from similar species like Polyommatus thersites (Chapman’s Blue).

🌸 Behavior and Ecology

• Feeds on nectar from a variety of wildflowers:
  • Bird’s-foot trefoil, dandelions, knapweed, clovers, and thistles
• Territorial males patrol and perch awaiting females
• Can form large colonies in ideal habitats, often with many individuals flying together

⚠ Conservation Status

• IUCN Red List: Least Concern
• Population trends: Stable in many regions, but:
  • Declines in intensive farmland and urbanized areas
  • Habitat fragmentation and pesticide use affect populations
  • Benefited by conservation of wildflower-rich grasslands and pollinator-focused agri-environment schemes

🔎 Interesting Facts

• Despite its name, females can appear mostly brown and be mistaken for other species.
• A bioindicator species, helping assess the health of semi-natural grasslands.
• Occasionally hybridizes with other Polyommatus species in overlapping ranges.

Would you like:

• 📷 Photos or illustration
• 🗺 Distribution map
• 🧬 Comparison with similar blue butterflies
• 📋 Checklist of key ID features

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