Tuesday, 21 June 2016

June 19th- The day I went abroad to find the Silver-studded blues.

I had never actually considered Cornwall to be abroad until I lived in Devon.

Devonians do seem consider Cornwall to be a foreign land, and I suspect the Cornish think the same about them. It's rooted in a rivalry that, as far as I can work out, comes down to the orientation of the crimp on a pasty (Devon is on top, Cornish in a semicircle round the side) and the order in which jam and cream are placed on a scone.

Anyhoo, delicious cultural differences aside, one of the Cornish speciality butterflies is the Silver-studded blue, a small and rather rare insect that hangs around- at its remaining strongholds- in colonies, sometimes many thousands strong. Who knows why? Probably as a form of defence. Maybe each individual thinks that it can call on the rest of the mob for support in the event that any old-school butterfly collector comes calling.

It's a species that I've never actually seen in the wild, despite over 40 years watching butterflies. We all have species like that, wildlife nemeses which for no particular reason simply elude us. Although I've been to places where Silver-studded blue were found, I've never seen one and I've never got around to actively seeking them out. So when I moved to Devon, it was high on my hit list.

Male Silver studded blue (Plebejus argus) 

One of the largest colonies in the country is down near Newquay at Penhale Sands, a sprawling dune complex spread over 6 square miles, some of it owned by the MOD. You often find that MOD land is good for wildlife. Our fauna and flora seems to prefer living in what is, basically, a war zone than amongst the general populace. It's a sad reflection of the human species.

The SSBs that I was seeking would seldom fly more than a half mile from their place of emergence. Indeed, they are reputed to be so reluctant to explore that you could walk past a colony of several hundred on the other side of a dune and never know a thing about it. (This is, I assume, because they live next door to a bunch of rifle-toting military types. Sticking an antenna over their sandy parapet could be the last thing they ever do).

I was at something of a loss to know how to find the colony in such a large hunting ground.

So I delved a little deeper into the web, to try and find a clue as to where the butterflies could actually be found.

And the web introduced me to the Cornwall Butterfly and Moth Society, who were planning a field trip to the very same Penhale Dunes the following day.

I phoned Lee from the society and booked onto the trip, hoping that the fact that I was coming from Devon wouldn't lead to any unseemly pasty-based friction (or my being detained as a foreign spy).

As I left home the following morning, it was raining hard and since I had a 2 hour drive to find them, I did rather question my sanity. However, as I crossed the border into Cornwall, I regained my sense of adventure and rather enjoyed the journey.

I kept expecting the rain to stop, but as I got closer and closer to my destination, it didn't.

The moors were covered in fog and lorries were putting up great peacock plumes of spray behind them. My windscreen wipers were having trouble keeping up with the water that was being deposited onto them.

When I got to the allotted lay-by,  I met Leon. He turned out to be the County moth recorder for Cornwall and clearly knew his stuff, recording all information in a small hardback notebook that he carries everywhere. A glance inside showed me that he undertakes a butterfly hunting expedition pretty much every day in the season- yesterday he had been up at Aish Tor in Devon, recording sightings of the High Brown Fritillary.

Since it was still raining, I was pretty dubious about seeing anything, but Leon was completely confident. He pointed out that when so many butterflies were concentrated into one area, there was really nowhere for them to hide.

Last week, he told me with a gleam in his eye, at a reserve down the road he'd seen a dozen on a single umbrella of Angelica. And his friend had counted over 80 in a two metre square. He spoke of a time some years ago when the population had got so numerous that they were like confetti when you walked.

'I'll believe it when I see it', I thought with a London ex-pat's cynicism.

We threaded our way through the dunes, pausing only for pyramidal orchids

We threaded our way through the dunes, pausing only for pyramidal orchids. Leon in his waterproofs nattering away happily about the aberrant form of the Grizzled Skipper that is found on the dunes, ab. Taras. Me plodding along behind him, my inappropriate deck shoes emitting a loud squelch with every footstep and my soaking jeans covered in grass seeds and sticking to my shins.

Eventually Leon paused and his eyes narrowed. 'There's one of the little so-and-so's" he said triumphantly.

And there it was indeed. A tiny butterfly, far smaller than I'd expected. Smaller than the Common blue, and with a more purple tinge to the upperside, and black bands evident on the males. I knew immediately that if I ever came across them again I would be able to identify them from the upperside alone.

The identifying clincher, though, is on the underside and it's where they get their name from. In the black spots at the edge of the hindwing are small groups of blue scales, which allegedly look like studs of blue. They're not a constant- some individuals have them very pronounced, others hardly at all and in some they are absent altogether.

The silver studs are a dead giveaway

Females, Leon informed me, though they lack the blue upper side, often have better 'studs'.

Like most blues, the females are brown. Which is just contrary, really.
Silver-studded blues are found in three distinct habitats- the dunes and calcareous grassland sites where the larval food plant is primarily Bird's-foot trefoil (Lotus corniculatus) and the adults are on the wing from June to mid July. But they are also found on heathland from July through August, where the larvae feed on Heather (Calluna vulgarise) and gorse (Ulex spp.)

As with many Blues, they have a close relationship with ants; in the case of the SSB, black ants in particular (Lasius niger and Lasius aliens).

Almost as soon as they hatch, the larvae begin to secrete a form of honeydew that the ants respond to. They pick up the larvae and transport them to their chambers within the nest, where they are tended and protected by the ants in exchange for supplies of the secretion. When pupation occurs, it is usually near the ants nest, and the pupa continues to secrete honeydew in exchange for protection until the butterfly emerges. Anecdotal accounts have the ants actually carrying the adult butterflies out of the nest to expand their wings, where they join the others in the colony.

Like most of these things, when you've got your eye in, you start to see them properly and it soon became clear that we were right in the middle of the colony, with hundreds of butterflies visible.

When you get your eye in, you wonder how you ever missed them

'If the weather was half decent', said Leon expansively, 'you'd see thousands'. I immediately determined to come back when the sun was out.

We experimented with shining a torch on them to see if they'd open their wings for us, and amazingly, it worked. Something to bear in mind for cloudy days in the future, as is the simple need for a pair of nail scissors to undertake the occasional bit of pruning before taking photographs. I had one chap with a lovely set of studs that insisted on hiding behind a blade of grass, and I couldn't get rid of it without disturbing him.

That moment when you realise you've forgotten your nail scissors.

Eventually, the discomfort of the rain took its toll. My spectacles were covered in rain and fogged up from my breath behind the back of the camera. I was drenched from head to foot and so much grass seed had stuck to me that if I'd slept on the ground, I'd have woken up in a meadow.

But I'd finally seen the Silver studded blue. And as I drove back across the border from the pouring rain of Cornwall into the pouring rain of Devon, I couldn't help thinking what a nice place Cornwall was.

Awfully wet, though.

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