I crept up on the butterfly as its wings flexed, pumping like delicate bellows, as it took in salts from dried dog urine. For a moment I thought it might be a fritillary – the upper sides of the wings were a rich orangeybrown with complex dark markings, the kind of colour unique to the old slide transparencies of Agfa film.
Then it detected my presence and flew up powerfully, manoeuvred in a seemingly random pattern, and settled on a leaf of yellow flag iris. I could see by the shape of its wings, like holes clipped from the edges of a bus ticket, that it wasn’t a fritillary but a comma butterfly.
The comma, Polygonia c-album, gets its name from the little white c-mark on the dead-leaf-camouflaged underside of its wings. The dictionary describes a comma as a phrase in punctuation that marks the smallest division of a sentence, the slightest interval or discontinuity; I was taught to read this as a, breath.
In the butterfly, the sentence is written in the wing markings; it flashes in a language only butterflies can read, and yet the closed-wing moment of a comma-breath seems perfect punctuation.
The French name for the comma butterfly is Robert le Diable, which is also the name of a favourite 19th-century Centifolia rose with a unique purple-cerise-scarlet-grey flower and a wonderful old rose fragrance; an 1831 opera by Giacomo Meyerbeer about the moral redemption of the son of a mortal and a demon; and the father of William the Conqueror, who was said to be the son of the Devil.
I don’t know how this fits with the butterfly, but something strange has happened to the species. When the growing of hops – the comma’s food plant – declined early in the last century, it just about hung on around the remaining hop yards of the Welsh Marches, until some time around the 1960s or 70s it began feeding on stinging nettle.
Since then the comma has become one of the most successful butterflies in lowland England and Wales, its range expanding north at more than 10km a year. A Faustian, pact?