‘Sinister’ – looking for web forms of white caterpillars on Sheffield trees at Manor, Batemoor and Jordanthorpe UK News

Readers got in touch with the Star after seeing what they described as cobwebs covering all of the trees – but experts say they needn’t worry.

A local told how he saw them near his home on Normancroft Way near Manor in the city.

He described the trees as “covered in silk” from all the thousands of caterpillars that had invaded the trees, which he said looked impressive.

They have also been spotted in other parts of the city.

Jess Ann contacted The Star to tell us about the same phenomenon on Whinacre Walk, Batemoor.

She said: ‘It’s just across my road – there are also loads of other infested in Jordanthorpe. This is madness ! They have invaded heaps of trees!

Similar phenomena were seen a few years ago on hedgerows near Bawtry, Doncaster, when small ermine moth caterpillars were thought to have formed the large communal network for their own protection.

Mark Parsons, moth conservation manager at Butterfly Conservation, explained the causes of the phenomenon.

He told the charity’s website: ‘At this time of year we often get reports of ghostly webs of silk covering sections of hedgerows and occasionally individual trees. Even though it may seem rather grim, don’t worry. The most likely culprit is a harmless caterpillar.

“These striking and obvious webs hide hundreds and sometimes tens of thousands of caterpillars of a group of butterflies called the lesser ermine butterflies.

Why do these species weave these webs and live together in such large numbers? It is a successful evolutionary strategy, providing protection from predators through security in numbers. However, the figures are difficult to hide and therefore the production of the silk canvas. “These webs and caterpillars are harmless and usually last from May to June. The webs slowly disappear over the summer and usually the hedge shrubs/trees recover. The adult moths fly later in the summer and all superficially resemble each other, being white or grayish with many small black dots, hence the name ermine.