Home › Xenos Bestiary › Psychneuein
At a glance
The Psychneuein is a giant wasp-like xenos creature, about two and a half metres long, that preys upon psykers. It does not hunt them for meat. It hunts them as hosts. The female Psychneuein projects its tiny eggs, each no larger than a grain of sand, psychically into the brain of a psyker. The eggs hatch within a day. The larvae eat the host's brain from the inside, pupate, and emerge as adults by the next morning, bursting out of the victim's skull.
These creatures are most famous for their role in the history of Prospero, the homeworld of the Thousand Sons. Long before the Imperium found that world, the Psychneuein almost destroyed its human civilisation. The people of Prospero survived only because they learned to control and hide their psychic powers. Their descendants became a society of scholars and sorcerers, and the Psychneuein became part of the legend of Magnus the Red and his Legion.
Anatomy
A Psychneuein resembles a huge wasp or hornet. It has a segmented body, a hard chitinous exoskeleton, multiple legs and wings that carry it swiftly through the air. Its body is long, about two and a half metres from head to abdomen, and it is a powerful flyer. Its senses are attuned to the warp. It detects psychic activity in the way that predators on other worlds detect the scent of blood.
Psychneuein swarms are terrifying sights. The buzzing of their wings can fill the sky, and their bodies glint in sunlight. On worlds where they have nested, entire populations have learned to fear the sound of their approach.
The life cycle
The Psychneuein's reproductive cycle is what makes it so horrifying.
1. The egg
A female Psychneuein senses a psyker nearby. Rather than attacking physically, she projects her eggs into the psyker's mind using her psychic abilities. The eggs, tiny as grains of sand, appear inside the brain. The victim often feels nothing at first, or perhaps a headache and a sense of unease.
2. The larvae
Within about a day, the eggs hatch. The larvae, described as small, spiny slugs, begin to eat the host's brain. The victim suffers increasingly severe pain, confusion and madness as their mind is consumed. Some accounts describe victims who lose their intelligence and personality bit by bit, until they are little more than empty shells.
3. The pupa
As night falls, the larvae pupate inside the host's skull. The victim is usually dead by this point, or unconscious and beyond help.
4. The adult
By the next morning, the adult Psychneuein emerge, splitting the host's head apart. They spread their wings, and the cycle begins again.
The speed of this process makes Psychneuein outbreaks extremely dangerous. A swarm can multiply quickly in any population with psykers, and on a world where many people have latent psychic abilities, it can cause a catastrophe.
The Plague of Prospero
Prospero was settled by humans in the distant past, and its population developed a high proportion of psykers. The Psychneuein found them. The swarms descended on Prospero's cities, and its people began to die in terrible numbers. Psykers were the prime targets, and Prospero had a great many psykers.
Prospero's civilisation came close to collapse. The survivors adapted in the only way they could. They learned to control their psychic abilities, to shield their minds and to stop them from shining in the warp. This discipline, born from desperation, became the foundation of Prosperine culture. When Magnus the Red arrived on the planet, he found a people steeped in psychic learning and self-control, and he built the Thousand Sons upon that tradition.
Even after Prospero's people learned to defend themselves, the Psychneuein did not vanish entirely. Swarms continued to haunt the ruined places of the world, and after the Burning of Prospero the creatures were still recorded among the ashes. Some scholars of the Inquisition have noted the bitter irony that the creatures that forced Prospero to master the warp may have helped set its people on the path that ended in Magnus's fall.
A legacy written in fear
The Psychneuein's mark on Prospero lasted long after the worst of the plague had passed. The society that grew from the survivors prized mental discipline above almost everything else. Children with psychic gifts were trained early to guard their minds, because an unguarded mind could draw the swarms. The great city of Tizca, with its pyramids, libraries and observatories, was built by a culture that had learned the hard way that knowledge and control were the difference between survival and extinction.
When the Thousand Sons settled on Prospero, they inherited this tradition. Their cults of sorcery, their obsession with understanding the warp and their belief that the Immaterium could be mastered all grew in soil fertilised by fear of the Psychneuein. The Legion's enemies would later argue that this confidence was hubris, and that the warp cannot be mastered. The people of Prospero might have answered that they had no choice. On their world, a psyker who did not learn control was simply food for the next generation of wasps.
Imperial xenologists have long wondered whether the Psychneuein reached Prospero by chance, or whether the world's dense population of psykers drew the swarms across the void. No answer has been recorded, and with Prospero burned and the Thousand Sons fled to the Eye of Terror, few remain who could investigate.
The Maran genus and the Webway
Other variants of Psychneuein are recorded. The Maran genus is particularly insidious. Its victims slowly lose their intelligence as the larvae grow, becoming dull and confused until the creatures finally erupt from them. Psychneuein are also said to be found in the Webway, the labyrinthine dimension used by the Aeldari, where they prey upon travellers with psychic sensitivity. The Aeldari, a deeply psychic race, have every reason to fear them.
Why psykers fear them
Psykers in the Imperium already live under the shadow of the warp, of daemons and of the Black Ships. The Psychneuein adds another layer of horror. It is a physical creature that uses a psychic power to target psychic minds, and normal defences are often useless. Psychic shielding, null fields and blanks such as the Sisters of Silence offer some protection, but the safest course is to destroy a swarm before it can approach.
The Imperium regards Psychneuein infestations as a serious threat. Worlds with high psychic populations, such as those that supply the Scholastia Psykana, are especially vulnerable. Outbreaks are usually dealt with by purging nests with fire and isolating affected psykers. Those infected are almost always beyond saving.
Defences
- Shield psykers with null fields, blanks and mental discipline.
- Burn nests at night, while the creatures are pupating or resting.
- Isolate the infected; there is no known cure once eggs are implanted.
- Avoid broadcasting psychic power in known Psychneuein territory.
- Purge swarms early, before they can multiply.
Trivia
- The Psychneuein is a key part of Prospero's history and the origins of the Thousand Sons.
- Its eggs are no larger than grains of sand.
- The creature's life cycle, from egg to adult, takes roughly one day and night.
- The Maran genus causes victims to lose their intelligence before death.
- Psychneuein are also found in the Webway.
