European Atlantic mixed forests

Old World Swallowtail (Papilio machaon) has appeared twice in the city this summer — once at Laeken on July 15, again near Chapelle on June 27 — suggesting that breeding may now be underway in urban Brussels rather than merely passing through.Females of this species stay close to their egg-laying plants, and the appearance of two individuals weeks apart in midsummer is a strong signal of established populations. Wild carrot on railway margins and other ruderal edges has become an anchor for the species here; warmer summers are steadily expanding the range of its host plants northward, opening ecological doors that were shut just a decade ago.

Broad Scarlets (Crocothemis erythraea) — a dragonfly of Mediterranean origin — have become a fixture at Brussels ponds only in this past decade. Between July 1 and 9, ten individuals were logged patrolling the water margins, expanding their range northward alongside warming summer temperatures. Their arrival marks a shift in the region's dragonfly fauna.Vagrant Darters and Blue Emperors were hunting alongside them — a combination of odonates that would have been unthinkable in these waters a generation ago. The pond community is being reshaped by climate, and what once seemed like vagrant records are now becoming the established summer guild.

Four-lined Giant Mayfly (Ephemera glaucops) appeared on the wing at Friche Josaphat in late June—a striking recovery for a species that vanished from urban Brabant by mid-century. The nymphs are burrowing larvae that spend two full years in stream sediment before emerging, which means their return signals two years of water quality good enough to sustain them through development.Caenis mayflies (both C. horaria and C. robusta) appeared the same week downstream at Domaine des Silex, with smaller mayflies documented at La Hulpe by week's end. Nine mayfly records across 60 days and 20 kilometers is not a surge—but it is a quiet signal. These insects were absent long enough that their return, even at low numbers, marks a meaningful shift in stream ecology and chemistry in this urban corridor.

Norfolk Hawker dragonflies (Isoaeschna isoceles) have been active across the Sonian forest ponds for two consecutive summers now — 76 records logged at Auderghem, Woluwe-Saint-Pierre, and Hoeilaart between late May and late June. This is not a coincidence. The species has a strict ecological requirement: its larvae develop in water soldier beds, and they cannot tolerate polluted water. The larvae feed in the floating rosettes for years before emerging.Two straight years of sightings at the same sites signals a genuine if quiet recovery in these forest waters. The presence of water soldier and the hawkers that depend on it is a marker of improving water quality — the kind of signal that takes time to accumulate and is easily missed without patient, attentive watching over seasons.This is recovery worth noting in a region where freshwater dragonfly communities have been under long-term pressure from eutrophication and habitat loss.

Rose-ringed Parakeets (Psittacula krameri) are now breeding across the city—68 sightings since January span the entire metropolitan area, from the northwestern suburbs to Tervuren. These are birds that escaped from the pet trade over decades, establishing populations through incremental releases and cage breaks. Each pair competes fiercely with jackdaws for nesting cavities in mature park trees, creating a quiet but measurable conflict for the cavity-nesting guild.Yet the ecosystem is not surrendering entirely. A Common Hedgehog (Erinaceus europaeus) was logged in Woluwe-Saint-Pierre this week—a native mammal increasingly rare in the urban fabric. Its presence, threatened as it is, reminds us that the older ecology still holds a tenuous foothold in the margins between the invasive and the domesticated.

The oldest trees near Pentagone hold moisture long after the sun goes down. Bark loosens from decaying trunks, leaf litter mats into layers along the roots, and the soil beneath stays cool even on the longest days of early summer. This is the habitat a fire salamander needs: not water exactly, but the dampness that collects where wood rots and invertebrates shelter. After dark, when the temperature drops and humidity rises, these animals move through it slowly and deliberately, working the ground with their tongues.Fire salamanders are not fast hunters. They are patient ones. A salamander will press itself close to a rotting log, tongue flicking to detect chemical traces left by earthworms, slugs, woodlice, and beetle larvae buried in the soft wood. The tongue strike itself is quick, but the approach is not. They cover ground methodically, quartering damp patches the way a dog works a scent trail, returning to productive spots on successive nights. Early summer is a critical feeding window for them. Females in particular are building reserves, because fire salamanders give birth to live larvae, small aquatic young that they carry internally until the larvae are ready to be deposited in a stream or seep. That investment is metabolically expensive, and the richness of summer invertebrate life in the leaf litter is what makes it possible.The spotted longhorn beetle connects to this indirectly, and the connection runs through the same rotting wood. Spotted longhorn beetles are flower visitors as adults, conspicuous in early summer on hogweed and bramble, but their larvae develop inside dead and dying hardwood, feeding on the decaying tissue for one to three years before emerging. The frass and soft galleries they leave behind create exactly the loose, moisture-retaining substrate that concentrates the smaller invertebrates a fire salamander hunts. A beetle larva in its gallery is also, occasionally, prey itself. Salamanders are not selective in the way a specialist predator is. If something soft-bodied and slow is present in the wood, and the salamander encounters it, it will eat it. The beetle's larval stage and the salamander's hunting range overlap in the same decomposing wood, and what the beetle larva modifies in the wood, the salamander's other prey then colonizes.The fire salamander is a threatened species here. Its presence near Pentagone depends on two things that urban green spaces often lack: standing deadwood left in place, and a water source close enough for larvae to be deposited. The European stag beetle, also recorded in this area and also threatened, shares the dependence on deadwood. Both species are indicators of something the site is doing right, that some of the old wood is being left to decay rather than cleared. The Asian lady beetle, an invasive species now abundant here, competes with native invertebrates for aphid prey and disrupts the food web at the smaller end, but its effect on the specific community of woodlice, worms, and beetle larvae that salamanders rely on is less direct.On a warm night in early summer, a salamander moving through the litter near a damp log is visible if you look slowly. The yellow and black patterning is not camouflage. It is a warning, advertising the toxic skin secretions the animal produces. Predators that have encountered one before avoid them. The pattern works because it is memorable, and it is memorable because it is so distinct: broad irregular patches of yellow against black, varying between individuals, consistent enough as a signal to be recognized. If you are out after dark near any of the older, damper tree stands at Pentagone, you might crouch beside a mossy log and wait. The salamander will come to you before you find it. Right now the ground is cool and damp beneath the canopy, and somewhere in that darkness a tongue is already working.

The ponds near Quartier des Quais hold the day's heat as evening stretches toward ten o'clock. If you're walking here now, step closer to the water's edge. The surface dimples and breaks as insects rise from below, and above them, dragonflies patrol in wide, deliberate circles.Scarce Chasers hang motionless in the air, their amber wings catching the slanted light. Four-spotted Skimmers dart between the reeds, each bearing the dark patches that mark their wing tips like ink spots on paper. Both species hunt with a precision that comes from compound eyes holding twenty-eight thousand lenses. They see movement in nearly every direction, tracking the smallest mayflies and midges that lift from the water in clouds too dense to count. A Scarce Chaser tilts forward, accelerates in a straight line, and closes its legs around a midge in a motion too quick to follow. It returns to its hunting post to eat.These longest days of early summer trigger the year's greatest emergence. Aquatic insects that have spent months or years underwater as nymphs sense the warming surface and rise together. Mayflies shed their nymphal skins at the waterline. Midges spiral upward in mating swarms. Caddisflies unfold their tent-like wings for the first time. The dragonflies position themselves in the air above this abundance, intercepting insects before they can disperse inland or complete their mating flights. A Four-spotted Skimmer can catch and consume dozens of prey in a single evening hunt. The invasive Asian Lady Beetles that cluster on nearby vegetation take smaller prey, but the dragonflies work the air itself, claiming insects that no ground-dwelling predator can reach.The light fades slowly, but the hunt continues. Dragonflies see well into twilight, their large eyes gathering the last photons of day. They patrol the same aerial territories they claimed at noon, following invisible boundaries marked by the best emergence sites and the most reliable updrafts. A Scarce Chaser hovers above a patch of water where mayflies continue to break the surface. The Four-spotted Skimmers work the margins, where emergent vegetation provides both perches and shelter for rising insects. This is the hour when the water releases its winter's work: all the larvae that fed and grew in the cold months now fuel the summer air. Listen for the dry whisper of dragonfly wings cutting through the evening quiet, and watch the water's surface catch the last light as it dimples and stills.

The meadows around Parc Leopold settle into dusk with the last calls of wood pigeons fading from the ash trees. Night brings a different kind of activity to these Brussels wetlands, one that requires darkness to reveal itself. Step outside if you can. Let your eyes adjust to the growing shadows between the hedgerows.In the grass beneath your feet, European glow-worms are beginning their ancient courtship. The females climb the tallest stems they can find, positioning themselves like tiny lighthouses in the vegetation. Each one carries a chemical lantern in her abdomen, mixing luciferin and luciferase with oxygen to produce a cold green light. No heat escapes this process. The energy goes entirely into illumination, a beacon that can shine for hours without burning the insect that makes it.The males patrol the darkness, their large eyes scanning for these pinpricks of bioluminescence. They are smaller than the females, built for flight rather than light production. Their compound eyes contain thousands of individual lenses, each one capable of detecting the faintest glow from thirty feet away. When a male spots a female's light, he lands nearby and begins his approach. The female can control her beacon, dimming it or brightening it as potential mates draw closer. She evaluates each suitor, and only the most persistent will earn the chance to mate. This threatened species depends entirely on this light-based conversation, conducted in a language older than human settlements in these wetlands. The females need tall, undisturbed grass to position their lights effectively. The males require corridors of darkness to navigate between glowing signals. Modern lighting disrupts both needs, washing out the subtle communications that have evolved over millions of breeding seasons.Other night hunters move through this same darkness. Bats patrol the airspace above the glow-worms, following echolocation maps that reveal flying insects invisible to human eyes. The invasive Asian lady beetles cluster beneath bark and stones, waiting for dawn to resume their hunt for aphids. Native ground beetles emerge from day roosts to hunt smaller prey along the soil surface. Each species has claimed a different layer of the night, dividing the darkness like territories on a map. The glow-worms occupy the narrow zone between ground and canopy, their lights threading through grass stems and low shrubs where their signals can travel farthest.Close your eyes and listen to the night settling around you. The temperature drops with the sun, and moisture begins to gather on the grass blades. Somewhere in the darkness nearby, if you are still and patient, you might catch the faintest green glow moving slowly up a stem, a female glow-worm climbing toward her spotlight moment in the Brussels night.