Woman’s bathroom find mirrors chilling behaviour seen in ‘The Last of Us’

Imagine stepping into your bathroom and coming across a scene that seems ripped from the pages of a horror novel. That’s precisely what happened to a woman whose unsettling find in her bathroom led to a discovery as fascinating as it is spine-chilling.

Last week, the woman noticed something peculiar next to her bathtub—a long, brown ‘string’ that seemed to be alive, curling and twisting without any visible head or tail. Nearby lay a dead huntsman spider, an ominous detail that would soon reveal a remarkable and somewhat macabre aspect of nature.

Upon seeking advice from a local field naturalists’ Facebook page, the woman who lives in central Victoria, Australia, learnt that the ‘string’ was likely a parasitic worm, specifically a mermithid nematode or horsehair worm. These creatures have a lifecycle that could be straight out of a horror movie, as they use spiders and other insects as hosts, devouring them from the inside out.

Dr Kayvan Etebari, an entomologist from the University of Queensland, explained the gruesome details of these parasites’ lifecycles. ‘Inside the host, both mermithids and horsehair worms develop by absorbing nutrients from the internal fluids of the insect or spider. They do this in a way that keeps the host alive and active for most of the parasite’s development,’ Dr Etebari said.

This survival is not out of kindness but necessity—the host must continue its normal activities until the worm is ready to emerge. When that time comes, the worm’s exit often results in the death or severe weakening of the host, typically near a moist environment conducive to the worm’s survival.

While these parasites commonly infect crickets, beetles, cockroaches, grasshoppers, and spiders, there’s a silver lining: they are not harmful to humans or pets. Birds and reptiles are also safe from these creepy crawlers.

The story brings to mind the infamous cordyceps fungus, known for infecting hosts and altering their behaviour, often with fatal outcomes—a concept popularised by the zombie series The Last of Us. Dr Etebari noted similarities between the two, particularly in their ability to manipulate the host’s behaviour driving them to seek out water, which is crucial for the worm’s emergence.

While the mechanisms behind this manipulation are not fully understood, the outcome is clear: the behavioural change ensures the worm exits the host in a suitable habitat. Despite taxonomic differences, mermithids and horsehair worms share similar strategies in their host manipulation.

These parasites are most often seen after rainfall or in damp areas where their insect hosts are abundant. If you find one in your home, Dr Etebari advises not to panic. The worm can be safely removed and placed outside in a damp area. They are harmless to humans and pets, cannot reproduce indoors, and will not infest your home. It’s an unsettling sight, but it offers a rare glimpse into the complex ecological interactions between parasites and their arthropod hosts.

In a twist that could be seen as nature’s poetic justice, scientists are now harnessing the power of microscopic nematodes as an eco-friendly pest management tool. These worms naturally seek out and infect soil pests, releasing bacteria that kill the insect and allow the nematodes to reproduce, thus providing a natural solution to pest control.

Remember, the world around us is full of wonders and, sometimes, the stuff of nightmares. But even in the most unsettling discoveries, there’s a chance to learn and appreciate the intricate balance of our ecosystem.

Have you ever encountered such a bizarre natural phenomenon in your own home? Or do you have other spine-tingling tales from the natural world? Share your stories in the comments below, and let’s explore the eerie yet extraordinary facets of nature together. 

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