How spiders turn the paradise island of Aitoliko into a horror movie set
Imagine the scene: hundreds of meters of coastline draped in thick white webs, like a giant shroud. Trees, bushes, and grass disappear beneath this ethereal blanket, creating a landscape straight out of your darkest nightmares. This is precisely what the Greek island of Aitoliko looks like when it's overrun by hordes of spiders.
Aitoliko is a picturesque island in western Greece, connected to the mainland by two bridges across the lagoon. Typically, this place delights the eye with turquoise water, cozy white houses, and lush Mediterranean vegetation. Locals enjoy fishing peacefully, while tourists enjoy traditional cuisine in waterside tavernas.
But once every few years, nature stages a true horror show here. Overnight, the lagoon's shores transform into the setting for a zombie apocalypse movie. The cause is a massive infestation of spiders, which cover the area in kilometers of sticky webs.
This terrifying spectacle is created by tiny spiders of the genus Tetragnatha, also known as stretcher spiders. Each one is no more than a couple of centimeters in size, but when millions of them gather together, the spectacle is truly impressive.
These arthropods typically live near water and feed on mosquitoes, midges, and other small insects. During normal times, their population remains unnoticed by humans. But when ideal conditions arise—warm, humid weather and an abundance of food—a population explosion occurs.
The Aitolico Lagoon is an ideal incubator for insects. The warm, stagnant water, rich in organic matter, becomes a breeding ground for mosquitoes and midges. When their population increases dramatically, spiders are treated to a feast they can only dream of.
Mass web-spinning is associated with the mating season. When temperatures rise above normal and the mosquito population simultaneously explodes, the tetragnathids begin to reproduce exponentially. They use webs not only to catch prey but also to protect their cocoons.
Well-fed females lay a huge number of eggs, from which thousands of spiderlings hatch. They all need a place to hunt, and the only way to avoid competition is to build communal webs. The result is massive: up to 300 meters of coastline are hidden under a dense layer of webbing, up to a meter high.
For local residents, this infestation is a real ordeal. The webs cover not only wild vegetation but also trees in gardens, vineyards, and lampposts. Walking along the shore becomes unpleasant—the sticky threads cling to clothing and faces.
But scientists reassure: Tetragnatha spiders are completely harmless to humans and animals. On the contrary, they are the island's true cleaners. Mosquitoes and small insects are always plentiful, and the warm, humid climate and abundance of fresh water create ideal conditions for the spiders.
Fortunately for the residents of Aitoliko, this nightmare landscape is short-lived. After a few weeks, the spiders complete their life cycle, lay eggs, and die. The webs gradually disintegrate under the influence of wind and rain, and nature returns to its normal state.
Scientists note that such mass outbreaks don't happen every year. They require a confluence of factors: an abnormally warm spring, high humidity, and an insect population boom. The last major outbreaks were recorded in 2018 and 2022.
No human intervention is required. After laying eggs, the spiders either scatter or die, and their webs disintegrate within a couple of weeks, exposed to sun and wind. The island's residents only slightly speed up the process by removing the thickest layers from beaches, roads, and around houses. They have long since become accustomed to their eight-legged neighbors and treat them calmly.
Strangely enough, this eerie phenomenon attracts the attention of not only scientists but also curious tourists. Photos of the ghostly coastline are spreading across social media, garnering millions of views. Some travelers make a special trip to Aitoliko in the hopes of witnessing this natural anomaly with their own eyes.
Ecologists view infestations as an indicator of ecosystem health. Massive mosquito populations may indicate a shift in the balance of the lagoon, perhaps due to rising water temperatures or pollution. In this case, spiders act as a natural regulator, keeping the insects in check.
Aitoliko isn't the only place on the planet where such a spectacle can be observed. Massive swarms of spiders and giant webs periodically appear in Australia, Pakistan, and the United States. In 2021, after flooding in the Australian state of Victoria, millions of spiders created webs that covered entire fields.
Scientists call this phenomenon "baluning," or mass migration. Spiders use their webs like parachutes to navigate to new territories. When thousands of individuals do this simultaneously, the result is incredibly eerie.
Aitoliko is a place where nature creates truly surreal landscapes every few years. Some see this as a mesmerizing miracle, while others see it as a reason to reflect on the delicate balance of the ecosystem. Would you dare to walk along the Aitoliko coast during a spider infestation, or would you prefer to observe this phenomenon only in photographs?