Wild Barcelona: A new generation of damselflies

They were dotted all over the wall, colourless, multi-legged forms, stuck firm to the concrete. A robin flew down to peck at one, but must have been disappointed to find it was merely an empty husk that floated weightlessly away.

It was Pedralbes park and early that June morning, before the gates were open, a generation of damselfly nymphs had emerged en masse from the pond and burst out of their unravelling skins.

The park pond is a stronghold of a diminutive damselfly with a long name, the western willow spreadwing. The whispering bamboo grove along one side provides a perfect site where they can lay their eggs in autumn. On hatching the following spring, the nymphs drop from the conveniently overhanging stems straight into the water.

Biology students monitor the pond life and have found three types of tadpole (water frog, tree frog and midwife toad) and various damsel and dragonflies. But not a sign of mosquito larvae. The spreadwing nymphs, who are a mainstay of this aquatic community, do a formidable cleaning job, their claw-like lower lip flicking out to snatch passing prey.

After the mass metamorphosis, most damselflies had dispersed, but I found one still clinging to its discarded skin, wings neatly folded together, not yet spread open in the characteristic position for which the species is named. You couldn’t help being struck by the small size of the translucent husk, abandoned only a few hours before. The slender abdomen, with its green metallic gleam, also seemed impossibly long.

When half emerged, the damselfly pauses and, like a balloon filling with air, its wings and abdomen are inflated into shape with hemolymph, the insect equivalent of blood. It’s a vulnerable moment, as the insect waits for its wings to dry out and harden before it can leave its watery habitat definitively behind and take to the air.

Lucy Brzoska runs nature tours and writes for www.iberianature.com