Here’s a detailed overview of the Green Hairstreak (Callophrys rubi), one of Europe’s most beautiful and widespread small butterflies.

🦋 Green Hairstreak (Callophrys rubi)

Taxonomy

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Lycaenidae
Genus: Callophrys
Species: C. rubi

Common names: Green Hairstreak
Scientific name: Callophrys rubi

General Description

The Green Hairstreak is a small, shimmering green butterfly that is widespread across Europe and Asia. Its distinctive emerald-green underwings make it one of the most easily recognized hairstreaks, though the uppersides are rarely seen as it rests with closed wings.

Wingspan: 25–30 mm
Upper side: Dark brown (seldom visible in rest)
Underside: Bright metallic green with a thin, faint white streak (often broken or absent)
Body: Small, compact, covered with fine hairs
Antennae: Black with white rings and orange tips

Distribution and Range

The Green Hairstreak has a wide Palearctic distribution, extending from western Europe to Siberia and northern China.

Found throughout:

Most of Europe (except far northern Scandinavia)
North Africa (localized)
Middle East and Central Asia
British Isles (fairly common in uplands and heathlands)

In northern latitudes, it inhabits lowlands, while in southern and central regions it occurs in upland areas up to 2,000 m.

Habitat

Prefers sunny, sheltered habitats such as:

Heathlands and moorlands
Woodland clearings and edges
Grasslands and scrub
Coastal dunes and slopes
Mountain meadows and limestone hills

Key habitat feature: Presence of larval host plants and warm microclimates with sparse vegetation.

Behavior

Flight period: April to July (earlier in the south, later in the north)
Generations: Usually one per year (univoltine)
Activity: Active in sunshine; males perch in open sunny areas to defend territories.
Resting posture: Wings always closed, showing green undersides.

They are strong fliers and frequently perch on shrubs, branches, or heather stems.

Diet

Adults: Feed on nectar from a variety of flowers, including:

Gorse (Ulex europaeus)
Bird’s-foot trefoil (Lotus corniculatus)
Bugle (Ajuga reptans)
Dandelion (Taraxacum officinale)
Bluebell (Hyacinthoides non-scripta)

Larvae (caterpillars): Polyphagous – feed on buds, leaves, and flowers of many shrubs and herbs, such as:

Common gorse (Ulex europaeus)
Broom (Cytisus scoparius)
Bilberry (Vaccinium myrtillus)
Buckthorn (Rhamnus cathartica)
Bird’s-foot trefoil (Lotus corniculatus)
Genista and Hippocrepis species

Life Cycle

Egg:
- Small, greenish-white, laid singly on flower buds or young shoots.
- Hatches after 1–2 weeks.
Larva (caterpillar):
- Flattened, slug-like, bright green with darker dorsal lines.
- Feeds openly but camouflaged against foliage.
Pupa (chrysalis):
- Brownish; formed in the leaf litter or soil at the base of plants.
- Overwinters in this stage.
Adult:
- Emerges in spring and flies for 2–3 months depending on climate.

Identification Summary

Feature	Description
Scientific Name	Callophrys rubi
Common Name	Green Hairstreak
Wingspan	25–30 mm
Color (underside)	Shimmering green
Color (upperside)	Dark brown
Flight Period	April–July
Generations	One per year
Habitat	Heathland, scrub, woodland edge
Host Plants	Gorse, broom, bilberry, trefoil
Overwintering Stage	Chrysalis
Conservation Status	Least Concern

Predators and Threats

Birds, spiders, and parasitic wasps prey on caterpillars.
Habitat loss through intensive agriculture, forestry, and scrub removal.
Pesticide use and loss of nectar plants reduce adult numbers.

Conservation Status

IUCN Red List: 🟩 Least Concern
Trend: Stable, but local declines in some regions due to habitat loss.

Conservation measures:

Maintain heathlands, open woodlands, and scrub areas.
Encourage native host plant growth.
Reduce pesticide use and overgrazing.

Interesting Facts

The green color of its wings comes from structural coloration, not pigment — light interference from microscopic wing scales creates the emerald tone.
Males are territorial and can be seen “perching” to defend sunny spots.
Despite its vivid color, it is remarkably well-camouflaged when resting among green leaves.
It’s the only green butterfly found in much of Europe.

Ecological Role

The Green Hairstreak plays an important role as a pollinator and as part of the food web supporting insectivorous birds and spiders.

Summary

The Green Hairstreak (Callophrys rubi) is a vibrant, small butterfly with dazzling green underwings, common across Europe and Asia. Thriving in heathlands, grasslands, and sunny forest edges, it is both adaptable and resilient. Its single annual generation emerges in spring, feeding on a variety of nectar plants and breeding on shrubs such as gorse and bilberry. Despite being small, it is a jewel of springtime landscapes and a key indicator of healthy semi-natural habitats.