04/06/2026
🌳Be alert to oak processionary moth caterpillars and their nests as we enter the peak season for this pest of oak trees. If you spot any, please report - more details below.
We're urging people to be alert to oak processionary moth caterpillars and their nests as we enter the peak season for this pest of oak trees.
The caterpillars – predominantly found in South East England – descend down oak trees in head-to-tail procession, earning them their name. They feed on the leaves as they move, which can negatively impact the tree's growth. This can weaken the tree and leave it more vulnerable to other stresses, such as diseases.
Oak processionary moth caterpillars are covered in long hairs that can cause itchy rashes, eye and throat irritation and should not be touched under any circumstances.
They also form silky white nests, ranging in size from as small as a 50 pence piece to as large as a melon. These nests discolour over the season, appearing dirty and brown by August. The nests also contain the hairs, and similarly should not be touched. The nests can be found on the trunk or the underside of branches of oak trees. Never try and remove or dispose of the nests yourself.
If you spot this tree pest, do not touch or get close to the caterpillars or nests. Please report the sighting via the TreeAlert portal: https://treealert.forestresearch.gov.uk/
Find out more: https://www.gov.uk/government/news/warning-on-oak-processionary-moth-issued-ahead-of-peak-season