Parents have been warned to keep their children away from hairy caterpillars and their nests because of the health problems they can cause.

Ealing Council issued a warning oak processionary moths could be nesting in oak trees in the borough.

Their tiny hairs contain a protein that can cause itchy skin rashes and, less frequently, eye and throat irritations and breathing difficulties in people and animals.

The council says it is working with the Forestry Commission to tackle the problem, which poses the greatest risk between May and July.

Councillor Bassam Mahfouz, cabinet member for transport, environment and leisure, said: “We are urging residents to be vigilant at home, in schools and any outdoor spaces where there might be oak trees.

“We know this is the time of year when the caterpillars build their distinctive white, silken nests and trails on the trunks and branches of oak trees, and can sometimes be as big as a tennis ball.

"They become discoloured and harder to see after a time. They may be interesting to a curious child or pet, so please take care and report any sightings to the Forestry Commission.”

These guys

The Forestry Commission has also advised oak processionary caterpillars only build their nests on the trunks and branches of oak trees, although they can sometimes be found in other trees.

They are never found among the leaves of an oak tree or on structures such as buildings, gates and fences, so caterpillars or nests in these situations need not be reported.

Anyone displaying symptoms, including skin or eye irritations following possible contact, should visit a pharmacist or call NHS111 for more-serious reactions. Contact a vet if an animal is affected.

Keep up to date with the latest news in west London via the free getwestlondon app.

You can set up your app to see all the latest news and events from your area, plus receive push notifications for breaking news.

Available to download from the App Store or Google Play for Android .