Written by Lucy Brzoska
In July the shadowy halls of Collserola’s shallow, trickling streams are filled with a spooky, fluttering presence.Groups of dark insects flicker in the half-light, or perch on isolated vantage points.
These are the male Copper Demoiselles, staking a claim for a stretch of stream. Their wings are black, and their bodies darkly iridescent, tinged purple like blackberries.When impressing the females, they kink their abdomens, revealing a red under-tip.This has saddled the species with the Latin name Calopteryx haemorrhoidalis
The common name, though, is inspired by the rich coppery tones of the female.She signals from a distance with white spots on sepia-coloured wings.
When a male, from his prominent lookout post, sees a female enter his zone, he’s immediately in attendance, serenading her in semaphore.The hovering wings form a cross, a performance being repeated up and down the stream.
After a successful courtship, the female is whisked up to a twig.
Eggs are deposited in a tangle of pink roots at the water’s edge.
Written by Lucy Brzoska
All round the pond, firmly stuck to the low concrete wall, were quantities of papery husks. I immediately suspected what they might be, remembering the concentration of mating Western Willow Spreadwings (Lestes viridis) in the park last autumn. It must have been a spectacular sight to see the nymphs emerge from the pond in such numbers and burst out of their unravelling skins.
One damselfly was still clinging to an exuvia, much smaller than itself. How could it fit inside? Reading up, I found that once half out, they pause and inflate their wings and abdomen into shape with hemolymph, the insect equivalent of blood.
Looking closely at one of the exuvia, it appears like a Mutoid Waste sculpture. The long “snout” is the labial mask, or lower lip, which the nymph flips open to grab passing prey.
The nymphs do their work well. The two biology students who volunteer to keep algae levels at a level acceptable for park authorities found no mosquito larvae in the pond at all.
After the mass metamorphosis, the damselflies had dispersed, but I did find one pristine young female clinging to a leaf. Her wings had a pink shimmer and were still held close together, not at the 45 degree angle that gives the species its name. With any luck, in a few weeks she would be laying eggs in the bamboo grove by the water’s edge.
Written by Lucy Brzoska
The plan was to walk along the small river that comes down from Montseny to Aiguafreda, marked on the map as the Riera de Pujol. It was a bit disconcerting to find a bone-dry river bed, but a few shallow puddles on the outskirts of Aiguafreda encouraged me to keep walking.A kingfisher hunting by a small dam was an even more hopeful sign.
The sporadic pools were linking up.A waterfall crashed down, where a man stood immersed up to his chin, eyes closed, exulting in the cold water.Up on the dusty track, the sun was scorching hot. Two women from the fire-prevention squad had parked their jeep and were refilling water bottles at the spring. I followed a path that dipped steeply under the trees.
It was like stepping into a church. At the end of the vault of trees there was a flat gravelly bank.Beyond that point the river deepened and levelled off, and the water grew still.On one side were smooth grey rocks, where a dipper had been perching, and the other bank was a tangle of vegetation in full blast of the sun.Boots flung off, I cooled down in the shade, and observed the scene.
There was a general commotion: iridescent damselflies flashed turquoise, clusters of butterflies fed, mated and basked, quantities of spindly water striders littered the water and light dappled on every surface.As usual when you sit in one spot for long, dimensions began shifting.Soon I was looking at a vast wilderness river, flowing by sheer grey cliffs and impenetrable jungle.Then I’d wade out into the canyon and, with water just above my knees, the world would shrink again.
The sunny bank was bustling with butterflies.Dusty pink Hemp-agrimony and a large dome of Wild Angelica were the most popular attractions, attended by a constant crowd of Silver-washed Fritillaries (Argynnis paphia).Any butterfly that fell into the water soon disappeared under wiry clumps of striders.
Most beguiling of all were the Beautiful Demoiselles (Calopteryx virgo), whose name goes straight to the point. The males would display their wings in a flash of dark blue silk, like peacocks.
The females are very metallic, a white spot on each of their four bronze wings, their abdomens a coppery green.
An impish damselfly perched on a twig, as if flown straight out of Dr. Caligari’s cabinet. Though in silhouette, the dark band of its narrow wings revealed it to be a female Copper Demoiselle (Calopteryx haemorrhoidalis).
Engrossed in damselflies, legs pleasantly chilled, a sharp pain made me look down.The mob of water striders were honing in for a nibble.
I retreated to the cool gravelly bank and lay listening to the water tumbling over rocks to fill the canyon. A waspish Large Pincertail (Onychogomphus uncatus – see Forum) settled on a stone. The dipper returned, flying low up-river.From this angle its white breast looked enormous.A Silver-washed Fritillary floated down like an autumn leaf.Occasionally a gust of wind would come up the valley, roaring in the tree tops, making the branches creak.It was a reminder of the hot world out there.It felt good down in the cool green vault.
I began to hear the sound of car doors slamming – post-siesta people coming to stock up with spring water.I walked up-river for a while, rock-hopping, and surprised a sparrowhawk who’d also been quiet down under the trees.