Black Hairstreak

The Black Hairstreak is one of our most elusive butterflies. It is found only in thickets of Blackthorn in woodlands on heavy clay soils between Oxford and Peterborough in the East Midlands of England. 

Underwings are brown with red edges, a row of black spots, a white streak, and small tails. Upperwings are brown with red edges. White-letter Hairstreak is similar but lacks row of black spots and has more obvious W-shaped streak.

The adults spend nearly all their time in the canopies of trees of dense scrub where they feed on honeydew secreted by aphids. At certain times they make short looping flights in and out of the tree tops with a peak of activity around midday.

The adults are easy to confuse with those of the White-letter Hairstreak and Purple Hairstreak which fly at the same time of year, care is needed to confirm the identification of the underside marking, which has a row of black spots in the outer orange marking and may have a white 'W'.

The Black Hairstreak declined steadily during the twentieth century and is now reduced to around 50 sites. Adult butterflies do not fly far and an entire colony will often confine itself to a single area within a wood, despite there being suitable habitat nearby. This inability to colonise new areas at a pace in balance with habitat loss, including hedge cutting, may partially explain the scarcity of this species.

Size and Family

• Family: Hairstreaks
• Size: Small/Medium
• Wing Span Range (male to female): 37mm

Conservation Status

• Butterfly Conservation priority: High  
• Protected under Schedule 5 of the Wildlife and Countryside Act (for sale only)
• A regional priority in East Midlands, East of England and South East England.

Caterpillar Foodplants

Blackthorn (Prunus spinosa) is almost exclusively used, but occasionally Wild Plum (P. domestica) and other Prunus species are used.

Lifecycle

Habitat

Most colonies breed in dense mature stands of Blackthorn growing in sunny, sheltered areas - usually along wood edges, edges of rides and glades or hedgerow thickets. Some smaller colonies occur in shady situations such as canopy gaps in mature woodland, small scrub patches or sheltered hedgerows. 

Distribution

• Countries: England
• Restricted to a small belt of central England running approximately from Oxford to Peterborough
• Distribution Trend Since 1970’s  = - 61%