A white line drawn on a bramble leaf is the map of a life. It catches the eye because of apophenia – a spontaneous perception of meaning in unrelated phenomena; it looks like writing, a signature or the number 20, and could be the year stretched out or something from a linear alphabet.
The line begins towards the middle of the leaf, squiggles a bit and follows the midrib to the leaf’s point. This kind of drawing is seen on many leaves and is caused by leaf miners: the grubs of beetles, flies, sawflies or moths that spend the larval stage of their lifecycle feeding inside a leaf, excavating a gallery before pupating and becoming an adult to fly away.
The structure, appearance and location of this white, evenly proportioned gallery drawn on a bramble leaf is diagnostic. It is the signature of the caterpillar of a moth called the golden pigmy, Stigmella aurella. It took a lifetime for the saffron-coloured caterpillar, chomping through leaf cells with opposable mandibles, spinning silk threads, to write this.
Its egg may have been laid by injection into the bramble leaf to hatch, tunnelling through spring to arrive at an exit point. Pupation marks that transition in insect metamorphosis where one life becomes another.
The creature that escapes its own labyrinth is not the miner, but a pilot. The adult moth it flies, with a wingspan of only 6mm, is a tiny wonder: dark and feathery with white and purple fascia, rusty headdress, copper-gold and metallic sheens. It is one of the commonest moths in Britain and Europe.
Bramble, like the rest of the rose family, is an insect magnet, and there are many leaf-miner species that live on it as parasites. The term is used as a pejorative: a blemish or disease that taints or degrades the host.
But plants are not isolated objects, they are places: their leaves are fields for grazing animals, their flowers sustain thousands of pollinators. Other plants, animals, fungi and microbes exist together with them in community. Sometimes this causes plant death, but in this case, the line that maps the golden pigmy’s journey from one existence to another is one of destiny.
