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Chalkhill Blue - Photograph by NBN Map - Chalkhill BlueMap courtesy of National Biodiversity Network (NBN)View full NBN Gateway profile

Chalkhill Blue (Male)

Males have milky blue wings with thin black-brown border and thin white fringe. Females brown with orange spots and blue dusting near body. A small, widespread butterfly that occasionally visits gardens. Females similar to Brown Argus, which lack blue dusting near body, and to female Adonis Blue, which have dark veins extending into white fringe on wing edges.

Resident

Range declining in some areas.

The male Chalkhill Blue is paler and, apart from the Large Blue, larger than other blue butterflies seen in Britain and Ireland.

At some sites many hundreds may be seen in August, flying just above the vegetation, searching for females. Large numbers of males may also congregate on animal dung and other sources of moisture and minerals. Females are much less conspicuous, being duller in colour, more secretive in their habits, and spending less time than the males in flight.

The butterfly is confined to calcareous grassland in southern England and has declined in some areas during recent decades.

Conservation status

  • UK Biodiversity Action Plan: not listed
  • Butterfly Conservation priority: medium
  • European threat status: not threatened
  • Protected in Great Britain for sale only

European/world range

Across most of Europe (excluding Scandinavia and areas south of 40B:N) eastwards to the Urals. Its range is stable through much of Europe but it has declined in several countries.

Foodplants

The sole foodplant is Horseshoe Vetch (Hippocrepis comosa).

Habitat

Both the foodplant and the butterfly are restricted to chalk and limestone grassland. The Chalkhill Blue breeds on all aspects but prefers south- and west-facing slopes and shorter turf.