Watch: Caterpillar infestation of 2021 likely to continue next year, expert says
Londoners are being urged to steer clear of nesting toxic caterpillars that are infesting the capital’s trees.
The caterpillars of the Oak Processionary Moth, which can cause itchy rashes and breathing difficulties in children and pets, are known to infest oak trees where they create “cottony hammock-like” nests.
The pests can also cause asthma attacks and vomiting people, while the larvae strip oaks of their bark and feed on their leaves, leaving trees vulnerable to disease.
The insects were accidentally introduced to the UK when oak trees from southern Europe were imported for a development site in Richmond in 2006. They spread to all 33 London boroughs and the Government has spent millions on pest control.
In 2015, inspectors found just 15 OPM nests in Hampstead Heath, Highgate Wood and Queen’s Park. In 2018 the number soared to more than 2,000.
Hounslow council has urged residents to stay vigilant to the species and stay away from infested trees on windy days and has been removing nests.
They are instructing the public to report any sightings of the caterpillars which are easily recognisable because of their long white hairs.
The greatest risk period is May to July when the caterpillars emerge and feed before turning into adult moths.
Hounslow Council’s tree management team have been removing nests from the Bedfont area with more planned as nesting intensifies in July.
Oak Processionary Moth
They move in nose-to-tail processions, in oak trees or on the ground, hence their name
The caterpillars have thousands of tiny hairs which contain an irritating substance called thaumetopoein.
The caterpillars can shed hairs when threatened or disturbed. The hairs can be blown by the wind and they accumulate in the caterpillars’ nests, which can fall to the ground causing rashes and breathing problems.
They live and feed almost exclusively on oak trees.
The undistinctive brown adult moths emerge in late summer, living for only four days in order to mate. They are not a health hazard.
Cllr Samia Chaudhary, Cabinet Member for Leisure Services, said: “I know many of you will be enjoying spending time in the borough’s beautiful parks and other green spaces with oak trees over the summer, but I urge you not to approach these caterpillars or their nests if you spot them and to prevent children from doing the same.
“It’s also advisable to minimise spending time under or in the downwind of any infested oak tree, especially on windy days during the summer.
“It’s important that residents should not attempt to remove the nests themselves.”
Residents can report a sighting to the Tree Alert service by visiting treealert.forestresearch.gov.uk
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