The butterfly only visible at 1,500ft

Michael McCarthy travels to the Lake District in the latest stage of our Great British Butterfly Hunt

Trying to see all Britain's 58 species of butterfly in a single summer is not easy – quite a few are found only in isolated localities – but only one really involves the sweat of your brow and the ache of your leg muscles.

The mountain ringlet is our one true montane or Alpine butterfly, for it is restricted to mountainsides in the Lake District and in the Scottish Highlands, usually at an altitude of between 1,500 and 2,500ft. Its flight period is a short fortnight or so from mid-June to early July, and when the sun goes in, so does the butterfly – it disappears into the grass in cloudy weather. All of which makes finding Erebia epiphron something of a challenge, and so last week, in The Independent's Great British Butterfly Hunt, we enlisted expert help, in the shape of two northern representatives from the charity Butterfly Conservation, Dave Wainwright and Martin Wain.

The principal problem was to locate an attractive insect, but one that did not stand out against its background and was no bigger than a wristwatch, in the vast and seemingly featureless expanse of the Lake District's high fells. We were fortunate in that we had a series of precise grid references where mountain ringlets had been seen in the past, and we based our search on them.

The area we chose to look was south of the Langdale Pikes, starting from the Wrynose Pass which leads from Langdale over the mountains into Eskdale. We began our hike up from a well-known Victorian landmark, the three counties' stone (marking the boundary of Lancashire and the old counties of Westmoreland and Cumberland), on a hot and sultry afternoon which necessitated a constant water intake.

We climbed steadily for about an hour and a half, and although we saw various butterflies, they were meadow browns, or small heaths, or painted ladies. We also spotted fascinating mountain birds – a pair of ravens, a wheatear, and several meadow pipits, and Dave Wainwright found and showed us a meadow pipit's nest, complete with two brown spotted eggs – but nothing resembling a mountain ringlet came into view, even as the air got cooler and we began to see the Lake District's peaks, with Skiddaw in the far distance.

Suddenly there was a shout from Martin, and I spotted him running across the slope, followed by Dave, who seemed to be trying to head something off. It was a mountain ringlet – they said. It might have been the man in the moon for all I could see of it, and as we carried on slogging upwards with nothing more appearing, and the sweat ran down my brow, I began to feel we would be out of luck.

But then there was another shout, from both men, and I spotted a little whirring ball of black with an orange halo around it. It was a mountain ringlet, buzzing over the grass, and then there was another, and another.

When we sat down to take a breather, we found there was a mountain ringlet resting in the grass stems just behind us, and we were able to look closely at its brown wings, each with an orange band containing "eyespots", which give the illusion of an orange glow when it flies. Eventually I had the best moment of all – a mountain ringlet on my hand, which seemed reluctant to fly off. I asked Dave how high we were, and the reading on his GPS said 614 metres – which is 2,014ft. On my hand was one of the hardest of all of our butterflies to see, and beyond was a staggering view of the Langdale Pikes with the Langdale Valley underneath. It was a very sweet moment.

Earlier, Dave and Martin had found us five more species of butterfly. On Arnside Knott, a limestone hill in north Lancashire, they led us to two spectacular species, the dark green and the high brown fritillaries (which we will profile at a later date) as well as the grayling and the northern brown argus, and at nearby Meathop Moss, just on the edge of the Lake District National Park, they found us the large heath (on which Dave – Dr David, to give him his proper title – is the world expert). With the mountain ringlet these six new species of butterfly brought our total seen to 41 – there are 17 to go.

Mountain ringlet Species 30 of 58 Erebia epiphron

Perhaps the hardest to see of all our butterflies, for this is a true mountain species and to find it means a hike into the hills. Dark brown, with a row of black-centred orange eyespots on the wings, it can be seen fluttering over the grass as low as 600ft in parts of the Lake District, but it is commonest between about 1,500 and 2,500 ft and has even been seen at the 3,000ft level. Most visible in strong sunshine.

Larval food plant: Mat grass, a typical heath grass of mountain sides.

Where seen: Mountain sides and mountain tops in the Lake District and in the Scottish Highlands.

Current conservation status: Difficult to assess owing to the remoteness and unpredictable weather of its mountain habitats, but its range appears stable.

31. Grayling Hipparchia semele

A butterfly of dry places such as heaths and clifftops which always rests with its wings closed, so its pretty brown and yellow upper-wing pattern is hard to glimpse; but its orange and yellow underside is attractive in itself, yet also excellent camouflage. There is concern about its dwindling numbers.

Larval food plant: Grasses such as sheep's fescue, bristle bent and marram grass.

Where seen: Commonest on cliffs, coastal heaths and sand dunes.

Current conservation status: A serious decline in recent years: 59 per cent down since 1976.

32. Northern brown argus Aricia artaxerxes

This is the northern version of a very similar species, the brown argus; although both are brown with orange wing bands, they are members of the blue family. The northern brown argus occurs from Lancashire northwards.

Larval food plant: Common rock rose, which has a lovely yellow flower.

Where seen: Sheltered sunny hillsides in the North and Scotland.

Current conservation status: 54 per cent down since 1979.

33. Large heath Coenonympha tullia

Another specialist: the large heath is our peat-bog butterfly. The dark English form, pale with spotted underwings, looks almost like a different species from the Scottish variety which is a much paler orange and has underwings without spots.

Larval food plant: Hare's tail cotton-grass or common cotton-grass.

Where seen: Boggy habitats in northern Britain, Ireland, and a few isolated sites in Wales and central England.

Current conservation status: Severe decline in range in recent years (more than 40 per cent).