No Blues, But Plenty Two's

It was on a warm, indeed very warm May Day when I found myself wandering a precipitous hillside in north Dorset. This spring has been most interesting weather wise. Following an unexceptional if mild winter, in southern England at least, we have had a long spell of dry weather, which recently moved up a gear and became quite warm. Anecdotally the average emergent signs of spring are showing around a week ahead. The house martins arrived early April, along with willow warbler, days later I had my first cuckoo and pied flycatcher and I heard my first swift over the house on April 29th  - usually they arrive around the 5th of May. And so, despite it only being May 1st I had already noticed reports of mid-May emerging butterflies on the wing. I got into the car.

An hour and a half after leaving home I arrived at my chosen site near Shaftesbury. It was 10.30am and 19oC on the car thermometer. During the drive over I mulled over the two butterfly species I especially wished to see, marsh fritillary (Euphydryas aurinia) and Glanville fritillary (Melitaea cinxia). Having been to this site before I knew where to look, but knowing where to look is a different proposition to actually finding what I'd be looking for. However I needn't have worried. The walk down the track immediately provided lepidopteran interest, accompanied by an incessant skylark song soundscape.

There were a number of brimstone pairs on the wing, close bonding flights with the male following the female as close as could be. I noticed at least half a dozen during my three hours on the hill. Small heath were everywhere, and in unexpected places. Even along the track dingy and less numerous grizzled skipper were patrolling along with spotted wood and small white flitting in and out of the hedge line, though only one red admiral today. I'd only walked a couple of hundred metres along the track, but now I needed to get onto the chalk hill proper.

Emerging through the hedge the view which always takes my breath away awaited me. Here on the bottom of the slope is a small, but functioning marsh fritillary population. I had the hill to myself other than the skylark song, now joined by a blackcap. 

A cinnabar was a nice find however it was while unsuccessfully trying to take a photograph of a small heath that a marsh fritillary flew slowly by. By flying what I really mean is wafting by, wings horizontal as they glide and flap low over the hill. I find this mesmerising. They are simply patrolling their territory, seeing off any intruders (small heath were given a serious telling off), but somehow that slow lazy flight reminds me of a jazz performer, super cool, unflustered and captivating, but like the words within a jazz lyric, the marsh fritillary means business. As I made my way along the slope a number of fights developed both with other marsh fritillary and other intruders. Spiralling up the pair, sometimes a trio, would twist and turn in rapid flight until it was over when the jazzlike victor would return to his super cool glide and flap quartering of the chalk grassland accompanied by the blackcap backing vocals. I was intruding.

It was getting very warm now so I decided to sit for a while at an area I'd found successful in previous years. This area looks no different to other parts of the hill, a few stunted hawthorn and a sizeable sheltered grassy area, but it is where marsh fritillary have, in the past, stopped and positioned themselves on a prominent plant. As they did on cue.

On this visit plantain and birds-foot trefoil seemed to be the preferred perching plant. I'd not been sitting for long when they appeared and offered a perfect pose for a few images. I don't own one of those huge lenses everyone seems to carry these days. When I'm out I travel light, water, a sandwich, binoculars and my trusty Canon SX50 bridge camera with a very good x 100 optical lens. At ten years old, like me, it is getting on now but it still produces the images I need. Binoculars are also a must while butterfly watching. Putting my camera away I watched the antics of the marsh fritillary through the power of a 12 x 42. So much more can be seen through binoculars, allowing a really in-depth visualisation of the butterfly and it's behaviour. Being this exposed on a chalk hillside however was warming me up a little too well. Time to move, back along the slope to the track where the Glanville awaited I hoped.

I just stumbled down onto the track (it is steep coming down the rickety steps) when I noticed  this pristine newly emerged marsh fritillary. So motionless was it that I thought it had died. The faintest flicker of its wings confirmed all was well. Clinging to the leaf, pumping its wings with blood it allowed me to really focus on the underwing. It all made me think, why so intricate a pattern, which while variable is unique to each species? Underwings are works of art, the combination of light and dark, spots and lines a clever use of the lepidopteran palette to attract a mate.

Interestingly while this marsh fritillary was on the bankside of the track, where the Glanville fritillary are, on the hill earlier I'd noticed a couple of Glanville's floating about. There is a tall raggedy hedge between these two areas, butterfly passage between this boundary is occurring, though the Glanville has somewhat exacting needs.

Initially I didn't see any Glanville's on the wing (actually they were a couple at the base of the hedge). I did however notice a copulating pair. I've never seen this before, not least as Glanville's are rare and not really meant to be here, being an un-licenced introduction it is believed around ten years ago. The most recent Butterfly Conservation report, 2024, states 'the introduced colony appears to be flourishing with several seen including a pair copulating'. Well in 2025 they're definitely copulating. 

Male and female Glanville look the same, however from my own observation the male is subtly 'sharper'. By that I mean the colour is a little brighter. boundary lines a little darker. Thus, if I'm correct, in these images the male is on the right. And of course there's another give away....

Settling down I spent some quality time with this pair. They were reasonably active, circling this hawthorn sapling, slowly it has to be said. Copulation wasn't continuous either. They'd separate and reorganise position before starting again, the male following the female nearly always in a clockwise direction. This pair had already been in embrace when I first saw them and for the next fifteen minutes or so they continued allowing me to really watch what was happening and take a few, well rather a lot of images.

Female left, male right

Male above

Male above

Female with wings open

Suddenly it was all over. One final embrace and then the female dropped to the ground, followed a few seconds later by the male. Which was when the fascinating behaviour occurred. The female clumsily wandered through the vegetation, followed a hairs breadth away by the male. As I watched the female came up to ribwort plantain and (I think, as she was partly obscured) began egg laying with the male watching on. This activity was on a very steep slope and I didn't want to disturb them, or damage the habitat by scrambling up to be closer, I was watching as close as I dared. Maybe I should have checked the underside of the leaf later for confirmation of egg laying, but I didn't as I'm one who prefers to stand back a little to let nature do it's thing unmolested. It is also why I find it frustrating when people wander through habitats, flattening the vegetation, in order to get that perfect image. The needs of the species we are observing should always come first.

Given though this pair were mating, then presumably egg laying on their host plant, ribwort plantain, I can give a good guess as to the outcome. This population of Glanville fritillaries in Dorset may be an un-licenced release, but it seems they're very much flourishing and on this precipitous bankside by a track, with plantains everywhere the future looks bright.

I met a trio of butterfly watchers coming down the track as I headed back to the car. They were interested to know if I'd seen any 'blues' today. They made me think, no not a single blue butterfly. This site is host to holly, small, common and Adonis blue. Despite the warm spring then it is still a little too early for the blues, but the twos are most definitely out in force.