Butterfly ID
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Field guide · Denmark
Blues, coppers and hairstreaks · Denmark

Common blue

Polyommatus icarus

Common blue is common in Denmark. Wing span: 24-32 mm. The flight period is from early May to late September, over three to four generations. The species lives in colonies in many different types of dry and warm locations, but it can be found, so to speak, everywhere in Denmark, especially as the males fly around considerably.

Status in this countryCommon in DenmarkLC (Least concern)
Common blue

Flight period

The flight period is from early May to the end of September, spanning three to four generations.

Habitat

The species lives in colonies in many different types of dry and warm locations, but it can be found, so to speak, everywhere within Denmark, especially because the males fly around considerably.

Identifying features

Wingspan: 24-32 mm. The upperside of the male is shining light blue with a paler ice-blue leading edge of the forewing, and with a very narrow, black costal margin (wing edge).

Similar species

common blue may be confused with many other Danish blue butterflies. An important feature is a single spot inward from or below the central spot on the forewing underside, often called the icarus spot. In Denmark Alcon blue and large blue may also have this spot; both are extremely rare.

Distribution

Widely distributed in Denmark. Can be found in most warm, dry, open, and flower-rich locations.

Biology

The larva feeds on many different species of leguminous plants. However, the most common host plant is bird's-foot trefoil.