Black hairstreaks found miles from their heartland

This rare species was only discovered in 1828. Now the population is enjoying a boom

The black hairstreak is a dark, elusive and rather plain little butterfly. And yet it inspires great passion, and not just because of its rarity.

There's something deeply restful and lovely about this midsummer insect, especially when it lets you creep close and admire it sunning itself on blackthorn.