As habitats go, this waterlogged ditch doesn’t appear to amount to much – a narrow channel holding a feeble stream, congested with bogbean and cottongrass. And yet this unpromising place is home to an endangered species, and one of our rarest: damselflies.
By this point in the summer, the flight season of the southern damselfly (Coenagrion mercuriale) is drawing to a close. Indeed as I wander this short gully at the western edge of Dartmoor, I find none. But the next generation is there, hidden just beneath the surface, tiny eggs peppering the aquatic vegetation. Soon the larvae will be hatching.
In July, this ditch was animated with damselflies. Bright needles stitched the air with colour, their slender bodies striped with horizontal barcodes of black – subtle markings that help differentiate one species from another. Among them were southern damselflies, thin filaments of light blue rising ahead of me as I walked beside the stream, inch-long abdomens patterned with pointed spears of black.
Unlike robust dragonflies, these exquisite damselflies are not strong flyers and seldom travel far from where they were born. This shallow and well-vegetated runnel is one of a handful of Dartmoor sites carefully managed for this insect, which is found in just a few scattered areas of southern England and Wales.
For such a threatened species, those I saw were certainly trying their best to sustain the population. Almost all were coupled up and flying in tandem – each egg-laying female clasped at the neck by a possessive male. I even spotted a trio strung together: a female held by a male who, in turn, was being held by another eager male not wanting to miss out. A bizarre three-in-a-reedbed conundrum, which I imagine took a while to resolve itself.
The scramble to pass on their genes is done; the water is no longer punctured by the pipettes of female damselflies, the sedge no longer decorated with threads of blue. It will be two years before this summer’s progeny take to the wing – fragile hyphens of life adding a dash of colour to this muddy moorland ditch.
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