Compare with: common blue

Holly blue Celastrina argiolus

Best time to see: mid Apr to end Aug

Key facts

A blue butterfly found along hedgerows and in woods and gardens

Habitat: anywhere with suitable breeding sites – native shrubs like holly, ivy or gorse

Widespread across southern England and Wales; numbers fluctuate greatly from year to year


Violet upperwings with broad black fringe; underwings silver-blue with tiny black dots; wingspan 35 mm

Flutters high up in trees or bushes and rarely settles on the ground; often rests on bushes with wings closed or half open


Eggs are white discs laid singly on the flowers or flower buds of shrubs, mainly holly and ivy

Caterpillars are translucent green and slug-like, feeding on berries

The dark brown chrysalis forms on the ground or in a crevice

© Gordon Chalk

© Tony Gunton