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. The male Chalk Hill 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.

Size and Family

  • Family: Blues
  • Size: Small/Medium
  • Wing Span Range (male to female): 38mm

Conservation Status                   

  • Butterfly Conservation Priority: Medium                                     
  • European status: Not threatened                             
  • Protected in Great Britain for sale only

Caterpillar Foodplant

The sole foodplant is Horseshoe Vetch (Hippocrepis comosa).  



The foodplant and the butterfly are restricted to chalk and limestone grassland.


  • Countries: England
  • Restricted to southern England, but not in far south-west
  • Distribution Trend Since 1970’s = -36%.

Chalk Hill Blue (male/upperwing) by Neil Hulme

Chalk Hill Blue (male/upperwing)

Chalk Hill Blue (female/upperwing) by Peter Eeles

Chalk Hill Blue (female/upperwing)

Chalk Hill Blue (male & female) by Dave Green

Chalk Hill Blue (male & female)

Chalk Hill Blue (male/underwing)

Chalk Hill Blue (male/underwing)

Chalk Hill Blue (egg) by Jim Asher

Chalk Hill Blue (egg)

Chalk Hill Blue (caterpillar) by Peter Eeels

Chalk Hill Blue (caterpillar)