I've seen some mysterious sights at work but this took me by surprise today. The entire tree 'moving' with caterpillars pic.twitter.com/s5W6ykIDHG— PC Rich Sutcliffe (@KiloSierra1728) June 10, 2018
Caterpillars, it seems, are not afraid to make big statements when designing their homes. Hundreds to thousands of the insect craftsmen covered a tree in Yorkshire, England, with so much of their eerie, white webbing that the result looks like a giant, moving ghost. Police officer Rich Sutcliffe recently found and snapped a photo of the tree while on duty in Northern Yorkshire, according to the BBC.
The so-called ermine moth caterpillars have a habit of draping their webs over random trees and other objects, according to Callum MacGregor, a postdoctoral researcher of biology at the University of York in the U.K.
Just last week, MacGregor captured some photos of the apple ermine moth (Yponomeuta malinellus) forming a similar web on a crabapple tree. Other news reports have shown that these moth caterpillars can also cover cars and other structures, according to the BBC.
Together, the insects "build these webs for protection from predators and parasites," MacGregor said. For example, many species of wasp lay their eggs inside caterpillars. When the wasp larvae hatch, they eat their way out and kill the caterpillars, according to MacGregor. "My guess would be that these webs are particularly effective at keeping these 'parasitoids' off," he said, referring to paristic insect larvae that end up killing their host. [Gallery: Out-of-This-World Images of Insects]
But they also feed on the tree as they cover it. Each caterpillar spins a bit of web to protect the part of the tree it's on. As it moves around the tree to find new leaves to feed on, it covers more and more of that tree, MacGregor said.
Ermine moths typically feed on deciduous trees, and though this blanket might damage the tree in the short term, it probably won't have long-term effects, he added.
"Although the tree is likely to experience a loss of productivity and a reduction in growth for the year in which it's covered in webs, it will be back to business as usual the following spring, when its next batch of leaves starts to grow," he said.
These blanketed trees and objects continue to take people by surprise — looking icy white in a backdrop of green, as if it had its very own veil of snow. But really, it's a bunch of tiny caterpillars hiding out from the dangers of the outside world.
Originally published on Live Science.