Caterpillars have covered an entire roundabout in silk.
The insects have stopped traffic in Croydon, south London, with motorists bemused about the webs.
Some fear it was made by spiders but it is actually the work of the ermine moth caterpillar, the Daily Mirror newspaper reports.
The National Trust's Matthew Oates said: "It's amazing - it's contemporary art and it's by moths rather than us. It's a protective webbing of silk they spin to protect themselves from predators and parasites.
"They can strip the leaves of whole bushes and small trees but the following year the majority recover if they are healthy. It is inspirational stuff."