Insect 🦋
🦋
Polyommatus icarus
| Size | 29–36 mm wingspan About the width of a 50p coin |
|---|---|
| Weight | 0.1 g Virtually weightless |
| Lifespan | 3–5 days as an adult |
| Rarity | Common |
| M vs F | Males are vivid sky-blue above; females are brown with orange spots — so different they were once described as separate species |
| Habitat | Flower-rich grassland, chalk downland, coastal dunes, road verges — anywhere with Bird's-foot Trefoil |
| Best time | May–September (two broods) |
| Conservation | UK: Green LC |
Did you know?
Common Blue caterpillars produce a sugary secretion that ants 'milk' like cows — in return, the ants guard the caterpillar from parasites and predators
Common Blue caterpillars produce a sugary secretion that ants 'milk' like cows — in return, the ants guard the caterpillar from parasites and predators
More for experts
Adults navigate using polarised UV light, reading patterns in the sky to orient when clouds block the sun — a compass invisible to human eyes
Often confused with
Holly Blue (lighter blue, no orange spots below), Adonis Blue (brighter blue male, chequered wing edge — chalk downland only)
Holly Blue (lighter blue, no orange spots below), Adonis Blue (brighter blue male, chequered wing edge — chalk downland only)