Birthday
HydrangeasPhotos of trees that look wrapped in silvery cotton wool could be stills from a fantasy film. Yet this is a real phenomenon: it is how spiders escape rising water. Here is where such landscapes have been seen, why they happen and whether they pose any danger to people or trees.
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Pakistan, 2010
In summer 2010 Pakistan suffered one of the most devastating floods in its history. Water lay across Sindh province for weeks, and millions of spiders climbed into trees to escape it. Soon the canopies were wrapped in dense cocoons of silk. Photos by British photographer Russell Watkins, who was working with a humanitarian mission, went around the world. Local people reported fewer mosquitoes that season than expected — perhaps some were caught in the webs, although there is no firm data on this.
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Where else it has happened
Similar scenes have been seen in Australia: in 2012, after flooding around Wagga Wagga, fields and shrubs were covered in continuous webbing, and in 2021 the same happened in the Gippsland region. Each time it followed a rapid rise in water.
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Why it happens
Many small spiders live on the ground. When it floods, they climb anything higher — grass, shrubs, trees — trailing silk behind them. Spiders can also “balloon”: they release a thread that catches the wind and carries them to a new place. When thousands of spiders do this at once on a small patch of dry land, the threads merge into a continuous sheet.
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Spider silk is remarkably strong: weight for weight, it is comparable to steel. That is why even fine threads laid in layers can stand up to rain and wind.
Is it dangerous?
These spiders are harmless to people: they are small species that pose no threat. The webs gradually tear and disappear as the water recedes and the spiders disperse. A dense cocoon may briefly reduce the light reaching a tree’s leaves, but the effect is usually short-lived.
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Autumn gossamer: the same thing in miniature
In Ukraine you can see spider ballooning every autumn. On warm, dry days silvery threads drift through the air as young spiders move to new territory. In Ukrainian this warm spell is called “babyne lito”, similar to an Indian summer.
Discover more remarkable trees in the most unusual trees in the world, and read about a tree that lives in water in bald cypress.
FAQ
Which spiders make these cocoons?
Usually a mix of small ground-dwelling species, including wolf spiders and money spiders (linyphiids), which are skilled balloonists.
How long do the webs last?
Typically from a few days to a few weeks: once the water drops, wind and rain break up the threads.
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Author: Maria Svitlovir
Graduated from Taras Shevchenko National University of Kyiv, Institute of Biology and Medicine (2001). BSc in Biology, MSc in Horticulture. Writes about plants, works at a garden centre selecting and repotting plants, and contributes to plant reference guides.
