Common blue

Common Blue butterfly male

Male Common Blue ©Zsuzsanna Bird

Common Blue

Common Blue ©Ross Hoddinott/2020VISION

Common Blue butterfly female

Female Common Blue ©Amy Lewis

Common blue

Scientific name: Polyommatus icarus
The common blue butterfly lives up to its name - it's bright blue and found in all kinds of sunny, grassy habitats throughout the UK! Look out for it in your garden, too.

Species information


Wingspan: 2.9-3.6cm

Conservation status


When to see

May to October


The common blue is a small blue butterfly that flies throughout the summer between April and October. The most widespread of the blue butterflies, it is found in a variety of habitats, including heathland, woodland rides, grassy meadows, parks, large gardens and waste ground. Caterpillars feed on clovers, restharrow, common bird's-foot trefoil and related plants.

How to identify

The male common blue has bright blue wings with a brown border and white fringe. The female is brown with a blue 'dusting' near the body. It has orange spots on the underside of its hindwings, whereas the similar holly blue has black spots. It is larger than the small and silver-studded blues, smaller than the rare large blue, brighter than the chalkhill blue, and lacks the black- and white-chequered pattern along the edge of the wings of the adonis blue.


Widespread, but absent from the Shetland Islands.

Did you know?

There are typically two generations of common blues in a year, but if the weather is warm, there can be up to three broods over the spring and summer.

How people can help

To attract butterflies, such as the common blue, into your garden, plant nectar-rich borders for them to feed along and climbing ivy and shrubs for overwintering insects.


Common blue butterfly on bird's-foot trefoil ©Tom Hibbert