16/06/2026
oak processionary moth caterpillar ALERT 🚨 🐛
(Article From Harlow Council)
Can be really harmful to humans and animals 🐕
Residents urged to stay alert after further OPM caterpillar nests discovered in Harlow
Harlow Council is asking residents to stay alert when visiting parks and open spaces following the discovery of additional nests of the oak processionary moth (OPM) in the town.
OPM has now been identified in at least two oak trees on public land. The latest findings confirm the pest is still active locally.
Originally introduced to England from mainland Europe in 2005, OPM is an invasive species that has become well established in Greater London and is now spreading across the southeast. Its caterpillars feed on oak leaves and present a risk to people and animals because of their toxic, barbed hairs, which can also be carried by the wind.
The council is responding by putting up warning signs, cordoning off affected trees and contacting nearby residents. Specialist contractors will carry out works to remove the nests safely.
Residents are being reminded not to approach or touch the caterpillars or their nests. Contact can lead to itchy skin rashes, eye and throat irritation and, in rare cases, breathing difficulties. Anyone experiencing a more serious reaction should seek medical advice, and pet owners should contact a vet if concerned.
The caterpillars are most commonly seen in late spring and summer. They are distinctive for the way they move in nose-to-tail processions and for the white, silk-like nests they build on oak trees, which can vary in size and darken over time.
Councillor Nicky Purse, Cabinet Member for Environment and Enforcement, said:
“We are continuing to deal with Oak processionary moth in parts of Harlow and taking the necessary steps to keep residents safe. This pest is becoming more widespread across the South East, so it is important people know what to look out for.
“If you are out and about and spot caterpillars or nests, please keep your distance and report it straight away. Do not attempt to deal with it yourself. By working together, we can help manage the risk and protect our community.”
All sightings on public or private land should be reported to the Forestry Commission using its online ‘Tree Alert’ system at www.forestresearch.gov.uk/tools-and-resources/tree-alert/
If the tree is in a council park, residents should also report it to Harlow Council on 01279 446655 or by email at [email protected]
Reports for privately owned trees should still be made to the Forestry Commission. These can also be submitted by telephone on 030 0067 442 or by email at [email protected]
The highest risk period is between May and July when the caterpillars are active, but nests should never be touched at any time.
