Black Hairstreak

Satyrium pruni

Oxfordshire, June 30th 2006

A sign in Oxfordshire woodland advertising the presence of this butterfly (though the above pictures were taken elsewhere)

This ancient picture of an ancient butterfly shows the first black hairstreak I ever saw, on 15th July 1986. It is taken in Oxfordshire.

The black hairstreak is a rare and elusive butterfly in England, surviving in just 40 or so colonies between Oxford and the East midlands. On the continent it does not seem to be significantly easier to find and all the black hairstreaks I have seen to date have been in England, in Oxfordshire.

The habitat requirement is dense, mature but not moribund, blackthorn thickets. For a long time it was not realised how much the survival of the butterfly depends upon correct coppicing. The traditional coppicing techniques (in central England, at least) are perfect, allowing the butterfly to move around suitable areas as old patches of blackthorn become useless for it. More modern coppicing uses a faster cycle and does not permit either the blackthorn or the butterflies to catch up - black hairstreaks are extremely sedentary butterflies. Now, all the remaining UK sites are managed correctly and although rare this species is not threatened.

On 29th and 30th June 2006 I spent many hours searching for black hairstreaks to photograph. In one wood (Shabingdon, near Oxford, on 29th) I saw a total of 8 different individuals in 5 hours but photography was well-nigh impossible because the blackthorn stands were high and the butterflies very restless, flying up into the canopy for no obvious reason at all. In another wood (Whitecross Green, on 30th) I found a similar density (maybe a little higher) but a few individuals were far more accessible. The best places were rides with relatively low blackthorn on both sides, and where both sides of the ride were illuminated by the sun. This meant a disturbed butterfly would fly across the ride rather than over the blackthorn and away!

In the middle of the day, black hairstreaks like to sit on leaves, blackthorn and other trees too, and rotate slowly around whilst supping honeydew. Sounds idyllic.