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Common Blue Butterfly

Polyommatus icarus

Common Blue Butterfly , Common Blue

Two mating Polyommatus icarus common blue butterflies

Hauhechel Bläuling, Polyommatus icarus Paarung

by CC BY-SA 3.0 at

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The Common Blue is a small blue butterfly that's in-flight from May to October. They're throughout the UK and mainland Europe, but numbers have declined due to habitat loss. They thrive in heathland, woodland and meadows; sometimes they'll end up in gardens too. The caterpillars aren't pests. They mainly eat Clover, Rest Harrow and Bird's-Foot Trefoil. Caterpillars of the Common Blue form a mutually beneficial relationship with ants. The ants will protect caterpillars in return for a nutrient-rich liquid secreted by the larvae!
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A pretty pollinator,


Adults: Males tend to be more consistent in their appearance, appearing a more vivid blue. Bright blue wings are enclosed within a pale brown border and white fringe. Females are much more varied in their appearance. Generally, they possess orange-brown markings along the edge of their hindwings. Some possess blue scales, whereas, in others, the blue colouring is completely lacking. When resting, the wings of both males and females appear bronze-brown with black and orange markings, the female appears darker in direct comparison. Larvae: Caterpillars are pale green, short and furry. They are active during the day. Eggs: The eggs are tiny, flat and white in colour. They are laid on the upper surface of plant species such as bird's foot trefoil.


These butterflies are attracted to areas where bird's foot trefoil grows in large quantities. They lay clusters of white, flat eggs on the surfaces of leaves.











The UK and Europe

Biological treatment

Caterpillars feed on wild, leguminous plants such as Lotus corniculatus. It's not advised to remove these insects from the environment due to the range of benefits they provide to the wider ecosystem.

Chemical treatment

It's not advised to use chemical treatments against this species.


Bird's Foot Trefoil

Lotus corniculatus

Red Clover

Trifolium pratense

White Clover

Trifolium repens

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