Unexpected Guests: OPM in the Oak
Last week, our team attended a mature oak tree for a routine reduction – but what we found in the canopy changed our plan entirely.
While carrying out our initial inspection, we discovered multiple nests of Oak Processionary Moth (OPM) – a hazardous pest that is becoming increasingly common across London and the South East. It wasn’t what we expected, and it meant we had to halt our work immediately and have a serious discussion with the client about next steps.
What is Oak Processionary Moth (OPM)?
OPM is an invasive pest that affects oak trees and poses a health risk to humans and animals. Originally from mainland Europe, it’s been spreading in the UK since 2006, especially in urban and suburban areas with large oak populations. The caterpillars form distinctive white, silken nests on trunks and branches and are known for their unique habit of moving in a nose-to-tail ‘procession’.
What makes them particularly dangerous is their tiny, barbed hairs. These hairs contain a toxin that can cause severe irritation to the skin, eyes and respiratory system. Symptoms can include itchy rashes, sore throats, eye problems, and even allergic reactions in some cases.
What We Found
In this case, the OPM nests were tucked deep within the canopy – easy to miss without a close inspection. It’s a reminder of how important it is to carry out thorough checks before any tree work begins, especially on oak species at this time of year.
We paused the job and carefully explained the risks to the client. Once we’d agreed a plan of action, we arranged for the nests to be removed safely by a specialist contractor licensed to handle OPM infestations. Only once the area was clear and deemed safe could we return to complete the tree reduction.
Why Safe Removal Matters
Because of the health risks involved, it’s illegal to remove OPM nests without the proper training and protective equipment. Attempting to do so can spread the hairs and increase the danger to both workers and the public.
At The Blue Tree Company, safety always comes first – for our team, our clients and the wider community. That’s why we take the presence of pests like OPM extremely seriously and follow all guidance from the Forestry Commission and local authorities.
What Should You Do if You Spot OPM?
If you see a nest or caterpillars on an oak tree – particularly between April and July – do not touch them. Instead, report your sighting to:
- The Forestry Commission via their Tree Alert tool
- Your local council if the tree is on public land
- A professional arborist, like us, for private trees
It’s best to keep pets and children away from the area and avoid disturbing the tree in any way.
OPM is on the Rise
We’re seeing more and more OPM activity, even in areas that haven’t historically been affected. The warmer spring temperatures and movement of infested materials (such as imported oak trees) have contributed to the spread. It’s something homeowners, councils and contractors all need to be alert to.
Need Advice?
If you’re concerned about a tree on your property, or if you’d like a professional inspection, don’t hesitate to get in touch. We’re here to help – and we’re experienced in working safely around OPM and other tree-related hazards.
Trees can be home to all sorts of hidden surprises. Some are welcome – like nesting birds or curious squirrels. But when it comes to pests like Oak Processionary Moth, it’s vital to act quickly and carefully.
Stay safe, stay informed, and always call the professionals.
