Earlier this year I helped put together a small pond in the playground at Ivydale Primary School in Nunhead. When it was first built, of wooden railway sleepers and rigid fibreglass insert, it may have looked a bit bleak, but I had faith that wildlife would find it soon enough. And they have.

Peering into the now clear water, after the initial algal bloom and water-flea dance auditions, I can see some squat mud-coloured gargoyles resting menacingly just below the water line. They are dragonfly nymphs (or sometimes naiads in North America), and they must be amongst the ugliest insects to be found.

Unlike their elegant, brightly coloured, glittering adult stages, dragonfly nymphs are stout and drab – perfectly adapted to life in the gloomy murk at the bottom of lakes, ponds and streams. I’d always imagined them as patient sit-and-wait pouncing predators. They have a bizarre hinged jaw mechanism, with the claw-like biting mouthparts perched on the end of an extending articulated proboscis, like an extra, seventh, limb that can suddenly jab forwards to snatch and grab a tadpole or mosquito larva. I don’t know how much sitting and waiting they normally have to do, but they are a lot more agile than I first thought. When I tentatively put my hand in to catch one it quickly scuttled out of sight into the depths.

Armed with a small kitchen sieve I eventually caught one. I’m not sure of the species yet, but a dragonfly rather than a damselfly. It seemed rather small and clumsy in my hand, but then I suppose it was rather like a fish out of water.