The butterflies of the Trevithick Trail

Emily Price

Recently a spell of warm and sunny weather has brought with it a welcome butterfly boom – far more impressive than last year’s washout, which saw one of the worst summers on record for the insects since 1976.

At the weekend, I took a long stroll along the historic Trevithick Trail in the South Wales Valleys in search of newly emerged butterflies.

The 9-mile long track beloved of cyclists and hikers carves its way through an abundance of diverse habitats perfect for wildlife watching no matter the time of year.

The route is named after Richard Trevithick – the inventor of the world’s first steam railway locomotive – and the pathway itself runs along the actual rail line of the the very first steam train.

Along parts of a peaceful stretch you can even still glimpse the 200 year old original sleepers that once anchored the tram rails in place.

Unmistakable

I’d barely set off on walk on Sunday when to my surprise, a striking orange tip butterfly fluttered down and chose one of the ageing stone sleepers as a resting place to bask in the early spring sunshine.

The males are easily recognisable with their unmistakable traffic cone orange wing tips, whilst the females have grey-black wing tips.

This particular male had chosen a shady spot on the edge of a hedgerow running along the Trevithick Trail where an abundance of garlic mustard had shot up – perfect food for the species – and a favoured plant for females to lay their eggs.

Orange-tip caterpillars are cannibalistic and when hatch they will eat their own eggshells before moving on to crunch up the unhatched eggs of other orange-tip butterflies.

Further along the abandoned railway line, a stunning showstopper of a butterfly flitted past me before coming to rest on a warm rusty manhole cover – a peacock butterfly.

Defence

The underside of its wings provides the species with excellent camouflage from predators – the brown and black dusky lines perfectly mimicking dead autumn leaves.

A peacock butterfly uses its outer wings as a rather beautiful defence mechanism with bright blue and yellow blotches set on striking orangey-red outer wings giving the illusion of large eyes that can startle or confuse potential predators.

Although for me, I’ve always fancied that a peacock butterfly’s multicoloured appearance looks more like one of my granny’s old crochet wool blankets.

Ten minutes further down the abandoned track, I startled as a flash of yellowy green wings fluttered close to my face before landing on a cluster of bluebells – a brimstone butterfly.

The species found in damp woodlands is a real harbinger of spring – emerging from their winter hibernation in March, it’s often cited as one of the first butterflies of the year.

In the sunshine, the males can appear to look almost fluorescent in colour whilst the females are far paler – almost white – although both have a small orange spot on each wing.

Their wing structures never fail to amaze me, their vein like appearance is almost identical to that of a leaf.

There is a rather lovely section of the Trevithick Trail near a very old crab apple tree now vibrant with blossoms that opens up to a large meadow overlooking the valley below.

The spot is marked with a stone crane holding a fish in its beak and has become the place I pause to enjoy a thermos of tea.

In 1804, locals too would have paused to watch in awe as Richard Trevithick’s Pendydarren Locomotive hauled a load of iron and people towards the canal wharf at Abercynon.

The now abandoned line runs parallel to the current Valleys Line where Transport for Wales services zip past every half hour.

Several years ago I avoided using the route as a wildlife watching patch because the loud screeching noise of pacer trains making their way between Cardiff and Merthyr Tydfil would frighten off anything I paused to admire.

Although I will never approve of the amount of trees that were cut down to make way for the South Wales Metro – I can’t deny that the new fleet of electric trains do pass through the area almost silently and are far better for the environment.

As the Trevithick Trail curves towards Quakers Yard Station, the woodland edges become denser with oak and pine trees dappling the sunlight in places.

It was here during my hike that I saw a rather smart looking speckled wood butterfly dancing in the shade before coming to land on the fresh new leaves of a blackberry bush.

This woodland specialist feeds on honeydew in the treetops and is likely to be the first and last brown butterfly you will see each year.

Both males and females are dark brown with creamy yellow spots – although the females are slightly paler.

Further down the trail, I spotted a highly territorial male speckled wood butterfly attempting to chase off a rival.

As the pair spiralled higher and higher, they were abruptly interrupted by a shiny new class 756 train on its way to the Welsh capital.

The updraft from the train blasted the two delicate insects into the sky.

They continued their aerial battle for a few seconds more before separating and rushing back to the shelter of a nearby glade.

I couldn’t help but think of the impact humans are having on the butterflies despite them being an integral part of the UK ecosystem.

Although the recent warm weather has offered perfect conditions for emerging butterflies – more than half of Britain’s butterfly species’ are currently in decline.

Climate change and the loss of flower-rich grasslands and heathlands are a large part of the problem as is the overuse of pesticides. 

Last year’s wet spring and relatively cool summer meant I didn’t see any butterflies along the Trevithick Trail at all.

It’s very sad to think that by the time the historic railway line reaches its third centenary it may be far more difficult for future wildlife watchers to enjoy spotting the same species I did on a glorious weekend in April many year before.