One of our rarest butterflies and one of the most recently discovered, due to the similarity with its close cousin, the White-letter Hairstreak. This species was first discovered in the British Isles in 1828 by a Mr. Seaman, an entomological dealer.
   Satyrium pruni is not a great wanderer and an entire colony will often confine itself to a single area within a woods, despite having a suitable habitat nearby. (The inability to colonise new areas at a pace in balance with habitat loss may partially explain the scarcity of this species.)
    The adults spend much of their time resting high in Maple, Ash or the larval foodplant, Blackthorn. They will crawl over leaves and twigs, in search of aphid honeydew from which they feed, making it extremely difficult to get a sighting.  However, they will come down to feed on various nectar sources, Privet and Bramble flowers being their part favorites.
   They have a very short flight period that peaks in the last 3 weeks of June.
   There is a single generation each year.
   When active, Black Hairstreaks are extremely difficult to follow in flight. (A typical characteristic of all hairstreaks.) To confuse matters, the Black Hairstreak is often found in the company of both White-letter and Purple Hairstreaks, and distinguishing these three species in flight is almost impossible.
   They always settles with wings closed and regulate their temperature by positioning their wings at an appropriate angle to the sun.
   When courting, males and females whirl around each other in a tireless dance which lasts for several minutes, resulting in the pair mating.
   The pupa is superbly camouflaged, looking like a bird dropping and is quite visible to the trained eye, attached to the upper surface of a leaf or twig.
   The pupal stage lasts around 3 weeks.