Blue butterflies

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Common Blue butterflies

The common blue butterfly is a butterfly in the family Lycaenidae and subfamily Polyommatinae. The butterfly can be found in Europe, North Africa, and the Canary Islands, but it is especially common throughout the British Isles. Recently, however, there has been an estimated 96% population loss for the common blue due to habitat loss. The butterfly’s name comes from the coloring of the wings. The males usually have blue wings with a black-brown border and a white fringe at the edge.

Scientific classification

  • Kingdom: Animalia
  • Clade: Euarthropoda
  • Class: Insecta
  • Order: Lepidoptera
  • Family: Lycaenidae
  • Genus: Polyommatus
  • Species: P. icarus
  • Binomial name: Polyommatus icarus

Blue butterflies Description

Polyommatus icarus has a wingspan of 28–36 millimetres. The dorsal side of the wings is an iridescent lilac blue with a thin black border. Females’ wings are brown with a row of red spots along the edges of the wings and usually some blue at the base. The extent of blue and brown is extremely variable depending on location. The top of the wings may be mostly blue, especially in Ireland and Scotland, but it always has red spots. The ventral side has a grayish base color in the males and a more brownish hue in the females

The common blue is common across almost the whole country. Males wait for females guarding their mating territory in trees and bushes. Females lay their eggs individually on the host plant on leaves or in flowers. The larvae have glands which secrete nourishing, sugary fluid that ants like to lick. In this way ants are attracted to the larvae, and their presence protects them.

Habitat Blue butterflies

The Common Blue can be in a variety of habitats, usually sunny, sheltered places where the larval foodplant can be found. Examples of habitats include; downland, coastal areas, undercliffs, road verges, quarries, disused railway lines, acid grass and woodland clearings.

It is also found on waste ground, disused pits and quarries, golf courses, and urban habitats such as cemeteries.

Blue butterflies Lifecycle

The common blue goes through two life cycles per year. The first brood usually emerges in May and lives until mid-June. The second brood emerges in late July or early August and lives until September.

  • Diet as caterpillars: leaves of plants
  • Diet as butterflies: wildflower nectar, excrement
  • Lifespan: 3 weeks as a butterfly


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. The Common Blue can be distinguished from the Holly Blue by the orange spots on the underside of the hind wings.

It is larger than the Small Blue, brighter than the Chalkhill Blue and lacking the black- and white-chequered pattern along the edge of the wings of the Adonis Blue (the latter two are found on chalky grasslands in southern England). It is larger than the Silver-studded Blue, which is found on heathland, and smaller than the very rare Large Blue.


Wingspan: 2.9-3.6cm


The Common Blue was accidentally introduced to North America at a Canadian airfield in 2005, probably arriving on board a plane, and is now spreading in the area.

Blue butterflies images

Image by M W from Pixabay

Also more: Chequered skipper butterfly

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