Brown argus Aricia agestis


Best time to see: mid May to mid Sep

Key facts

A brown butterfly of open chalky grassland

Habitat: open chalk and limestone grassland where plenty of its caterpillar food plant, rockrose, occurs

Confined mainly to southern England and the Welsh coast; once scarce in Essex, in the 90s it has made a strong comeback

Recognition

Upperwings dark brown with crescent-shaped orange marks round the edges; underwings paler with black spots

Fly freely over open ground; roost communally on clumps of grass; wingspan 29 mm

Males gather in sheltered spots to wait for mates

Lifecycle

Eggs are pale white discs laid on the stems of Rockrose or Geranium in late May and again in August

Fleshy green caterpillars feed on leaves, usually attended by ants

Ants bury the chrysalis in the earth; adults emerge in May/June and again in August/September

  • Main photo
  • underside

Photo © Gordon Chalk

Photo © Dennis Carter