(Patagonia’s Untold Stories)
Scraping sand grains and pebbles for nutrients, it has wandered the river bed for ten months. After hiding from predators under submerged rocks it is time to leave the safety of the river behind.
Primitive crane fly (A. gloriosus) collection site. PHOTO BY R. ISAÍ MADRIZ
Among the rarest species of insects in the world, Araucoderus gloriosus belongs to one of four primitive crane fly species found in South America. Is its rarity a result of what is happening?
Its instincts drive it in search of entangled root mats of marginal vegetation. For that, it must cross a hazardous field of exposed cobblestone. Its body is being pulled against the moist rocks. The unfamiliar sensation of gravity is sobering.
Devoid of legs, it pulls its heavy body forward with its mandibles.
Dawn enshrouds the river bank with a dense mantle of fog. There, not too far from the river’s edge, partially compressed between two fist-sized rocks, the putrid pupal remains of another of its kind is being consumed by scuttle fly larvae; an ominous sign of what lies ahead.
The chaotic arrangement of the rocks and the impoverished diatom film covering them, laid evidence of a violent recent flood, a humbling reminder of the power of the elements.
If it is to survive, the larva must hurry. The morning sun’s rays will soon dissipate the fog, exposing the migrating larva to predators.
It has begun. Hungry ground-dwelling birds scout the surface, while other small passerine birds circle above looking for an easy meal. Deadly parasitic wasps are in search of prey; their young will consume their host from the inside out.
The fourth molt allowed the eyeless larva to develop light-metering primitive eyes, an elemental predatory avoidance tool.
Scanning Electron Micrograph of Primitive crane fly (A. gloriosus) larval head capsule. Photo by R. Isaí Madriz
Halfway from the marginal vegetation, it begins to burrow into the moist sand.
As I observe sitting motionless on top of a large rock I ask myself: Was the drastic behavior change triggered by the continuous sensation of morning rays? Is the larva aware of the constant danger from predators? Perhaps it senses imminent risk of desiccation.
As the day passes by I wait patiently. The night belongs to bizarre creatures. Found only in Patagonia, stoneflies over two inches in length are taking over the night. Emerging in mass, they invade the land in search of a safe place to complete their transformation to adulthood.
At last, the larva reached the entangled root mats of the marginal vegetation. It searches for a secure moist area to begin its transformation. Pupation is the most vulnerable stage in its life cycle.
Its larval skin has been shed. The thin and translucent pupal skin presents a unique view to its internal organs. Highly sensitive long hairs arranged in crucial areas of its body alert of changes in its surroundings.
Safe in the moist microhabitat, its clear skin darkens with the passing days. Within, its organs reorganize for the last time.
A few days pass by and the pupa’s skin is hardened, a promising indication of a successful metamorphosis
Primitive crane fly (A. gloriosus) pupa habitus ventral (left) and lateral (right)view. Illustration by R. Isaí Madriz
High above, recent snowfall failed to remain on the mountaintop. An unexpected flood engulfs the river bank, dislodging the pupa from its shelter. Trapped in the increasing current, the river gradient steepens, as whitewater fills the increasingly narrowing channel.
Unable to move its developing appendages, the pupa relies on buoyancy for survival. It must keep the two respiratory organs on its head above the water or it will drown.
Several hundred yards downstream, in a small foamy pool in the splash zone of a 20ft waterfall, a newly emerged adult male hangs on to the vertical side of a small rock, its discarded pupal skin floats among plant debris. With luck he will spread his wings for the first time.
Nearby, holding on to the exposed roots in the undercut riverbank, a female completes her metamorphosis. At the same time, hanging from the marginal vegetation, camouflaged by their exquisite coloration, males wait for receptive females to take flight.
The male at the base of the waterfall flies away in search of a warmer, drier place away from the cold mist. As I wade through the river, following the male’s path, I feel the soothing sensation of the sun warming my skin. The male’s adult body is being illuminated by the sun for the first time. Does he feel the same calming sensation as I do?
Its dull flight pattern and slow speed diversify, as the morning rays stimulate a graceful aerial dance revealed for the first time before my eyes. I stand motionless in the middle of the river, in awe. The exquisite wing pattern is complemented by an iridescent hue reflecting the sun’s rays. This fly is indeed glorious.
Stacked image of the Primitive crane fly (A. gloriosus) adult hanging from a Magellan’s beech (Nothofagus betuloides) branch. Photo by R. Isaí MadrizR. ISAÍ MADRIZ collecting A. gloriosus larvae. PHOTO BY Gregory R. Curler
In a blink of an eye the magic dissipates. The male is tackled out of the air and onto the overhanging vegetation by a dragonfly several times his size. The predator perches on a broad leaf a few feet away from where I stand. I watch in shock, as it slowly consumes the primitive crane fly, discarding the legs and wings as it gradually devours the thorax. Several thoughts run through my head: How does the fly process pain? Does he? What thoughts would be passing through the fly’s brain? Does he have any?
In the upcoming days little more is revealed of this species’ secretive adult behavior. The population size is a fraction compared to what it was two years prior. With adults becoming increasingly harder to find, their short adult life span and the ever-changing weather make the task at hand troublesome.
With the season passing, the adult population vanishes. It is cold, but the mountaintops have yet to retain any snowfall. Weather fluctuations turn what should be snow into rain, preventing accumulation of snow and consequently scouring the riverbed through the intensifying glacial melts that feed the river. Can this species survive the ongoing climatic challenges, or will it embrace the imminent fate of the bleeding glaciers that it fully depends on?
* The story above is an accurate assemblage of observed field events from 2013–2018 complemented by a scientific investigation on the species depicted.
Equipment used for this nine month project is courtesy of Fulbright, National Geographic, Iridium, Alpacka Raft, Aqua-Bound, Boo Bicycles, Kokatat, Seal Line, Osprey, Tentsile, Patagonia, Voltaic & Jax Outdoor Gear.
Originally posted 2018-04-21 04:19:01.