Posted by: David Green | July 1, 2010

More on Blue Butterflies

Blue butterflies tend to live in colonies. If they become isolated, evolutionary processes often produce distinctive forms or subspecies. One of the more interesting of these is the caernensis form of the Silver Studded Blue which reaches its (current) northern limit on the limestone slopes of the Great Orme near Llandudno.

The rare caernensis form of the Silver Studded Blue often shows conspicuous blue scales on the upper wing of female butterflies.

The Silver Studded Blue was once much more widespread in the British Isles, with colonies as far north as Lancashire, Cumbria and even Scotland. Its decline in the twentieth century is the result of  changing agricultural practices. The major threats to this species are heathland destruction, and the fragmentation of its habitat. Like many other blue butterflies it relies on ants in its larval and pupal stages and as with the Large Blue, to look after the butterfly you must look after the ants.

Silver Studded Blues can be distinguished from the Common Blue by the absence of a black spot more than halfway down the forewing.

The Great Orme is busy at weekends, so I set off on Sunday to track the butterfly down at a nearby but less well known site in the Dulas Valley. The Silver Studded Blue was introduced here about 50 years ago and it seems to be doing well. One of the best places to find it is the Mynydd Marian nature reserve, a popular place for climbers, but not well known among naturalists.

South facing limestone slope with Valerian at Mynydd Marian Nature Reserve. Ideal habitat for the Silver Studded Blue.

The reserve has a south facing limestone slope and the butterfly is common here. There are plenty of other species too including the Small Tortoiseshell, once extremely common, but now rather less so, Common Blue, Small Heath, Red Admiral and Painted Lady.

A Small Tortoiseshell, once a common sight, but I now get excited when I see one!



  1. Stunning pictures David.

    It is really great to know these are on our doorstep!

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