sanctuaryofwings
Mazarine blue (Cyaniris semiargus), a species in the family Lycaenidae.
Photo: Didier Descouens · Wikimedia Commons · CC BY-SA

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Contents
  1. Identification
  2. Range and habitat
  3. Life cycle and host plants
  4. Behaviour and flight period
  5. Conservation
  6. Similar species

The Mazarine blue, Cyaniris semiargus, is a small blue butterfly of the family Lycaenidae, found across the grasslands of continental Europe. It is widespread and fairly common on the continent, especially in southern and eastern Europe, though it formerly occurred in the southern half of England and is now extinct in Britain and Ireland.

Identification

The Mazarine blue is a small butterfly, with a wingspan of 32 to 38 mm, males running 32 to 36 mm and females slightly larger at 34 to 38 mm. The sexes differ clearly on the upperside: the male shows the violet-blue that gives the species its name, while the female’s upperside is a duller brown, sometimes with a dusting of blue scales near the body. The underside of both sexes is pale grey-brown with a row of small black spots, lacking the orange markings seen in several related blues.

Range and habitat

On the European continent the species lives in flowery meadows and grassland, from low elevations up to about 2000 m. It once occurred in the southern half of England as well, but is now extinct in Britain and Ireland, surviving today only on the continent.

Life cycle and host plants

The caterpillar’s main foodplant is red clover (Trifolium pratense), with kidney vetch (Anthyllis vulneraria) and gorse (Ulex europaeus) also recorded. The species overwinters as a caterpillar, an early instar larva that resumes feeding on clover shoots the following spring. There is a single generation a year.

Behaviour and flight period

The Mazarine blue has one brood a year in all locations. In its now-extinct British Isles population, adults flew from mid-June to mid-July; the species is believed to form discrete breeding colonies both there and on the continent.

Conservation

Its IUCN category, shown in the facts box, comes from the species’ Wikidata record. Despite its disappearance from Britain and Ireland, the Mazarine blue remains common across much of continental Europe.

Similar species

  • Common blue (Polyommatus icarus): a more widespread blue sharing similar grassland habitat, told apart by its orange-spotted underside, which the Mazarine blue lacks.
  • Silver-studded blue (Plebejus argus): another blue of similar size and range, distinguished by the metallic blue-green scales at the base of its hindwing underside spots.

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