The black hairstreak is the UK’s rarest hairstreak but is more widespread in Europe. In the UK, it is only found in woodland in the east Midlands, particularly sites in Oxfordshire and Buckinghamshire. This species does not travel or disperse over great distances.
How to identify
The upperwing is brown with orange spots. The underwing is brown with an orange streak. There is a row of black spots near the margin and a thin white streak across the underwing. It is very similar to the white-letter hairstreak and these species are extremely difficult to distinguish whilst in flight. Older caterpillars resemble the blackthorn leaves which they feed on.
Where to find it
Black hairstreaks are mostly found in mature blackthorn hedgerows and woodland rides where their larval foodplant blackthorn is abundant. Adults are very hard to spot as they spend most of their time in the canopy of ash trees where they feed on honeydew secreted by aphids. Very occasionally the caterpillars will feed on other plant species.
When to find it
How can people help
The Wildlife Trusts manage many woodland nature reserves for the benefit of butterflies: a mix of coppicing, scrub-cutting, ride maintenance and non-intervention all help woodland wildlife to thrive. You can help too: volunteer for your local Wildlife Trust and you could be involved in everything from traditional forest crafts to surveying for butterflies.