The Long-tailed Blue is an exotic migrant from the Mediterranean with a handful typically reaching UK shores each year, but experts believe climate change is behind this butterfly reaching our shores more regularly and in vastly increased numbers.

One of the largest migrations took place in 2015 when 60 adult butterflies crossed the Channel in August and laid 1000s of eggs in gardens and allotments along the South Coast.

The butterfly gets its name from the wispy ‘tails’ on the trailing edge of each of its hindwings, which flutter in the breeze. Adjacent eye spots fool birds into thinking this is the head of the butterfly, allowing it to escape any attacks unharmed.

The male is a striking violet-blue colour, while the female is a mix of duller blue and brown. The underside of both sexes is a sandy brown colour crossed by numerous white, wavy lines.

Size and Family

  • Family: Blues
  • Size: Small
  • Wing Span Range (male to female): 32-42mm

Conservation Status                  

  • Butterfly Conservation priority: Low
  • European status: Stable

Caterpillar Foodplants

Caterpillars feed primarily on plants in the legume family, including Bladder-senna (Colutea arborescens), Broad-leaved Everlasting-pea (Lathyrus latifolius), Broom (Cytisus scoparius) and Narrow-leaved Everlasting-pea (Lathyrus sylvestris). Mange-tout pea (Pisum sativum) is also used.

Habitat

The adult butterfly is most-often seen flying around garden flowers, especially those which are potential foodplants. However, it may also be found on open downland.

Distribution

  • Countries: England, Scotland
  • Most records are from the south of England and occasionally further north. A rare immigrant with a concentration of sightings from coastal counties and the Channel Islands.
Long-tailed Blue (male) - Bob Eade

Long-tailed Blue (male)

Long-tailed Blue (male/underwing) - Iain Leach

Long-tailed Blue (male)

Long-tailed Blue (female) - Iain Leach

Long-tailed Blue (female)

Long-tailed Blue (female/underwing) - Iain Leach

Long-tailed Blue (female)

Long-tailed Blue (mating pair) - Bob Eade

Long-tailed Blue (mating pair)

Long-tailed Blue (male) - Iain Leach

Long-tailed Blue (male)

Long-tailed Blue (male/upperwing) - Leigh Prevost

Long-tailed Blue (male/upperwing)

Long-tailed Blue - Bob Eade

Long-tailed Blue

Long-tailed Blue (egg) - Peter Eeles

Long-tailed Blue (egg)

Long-tailed Blue (caterpillar) - Peter Eeles

Long-tailed Blue (caterpillar)

Long-tailed Blue (caterpillar) - Peter Eeles

Long-tailed Blue (caterpillar)

Long-tailed Blue (pupa) - Peter Eeles

Long-tailed Blue (pupa)