Cluster of Oak Processionary Moth caterpillars on tree bark with the text 'Combating Oak Processionary Moths: Protecting Our Trees'.

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Oak Processionary Moth caterpillars on mossy tree bark with the text 'Common Signs of Oak Processionary Moth Infestation' and the Green Canopy Tree Consultancy logo.

Common Signs of Oak Processionary Moth Infestation

5-8 Min Read

Identifying the signs of Oak Processionary Moth (OPM) infestation early can help protect the health of your trees and the safety of your community. This article will guide you through the visual signs of OPM, the symptoms in trees, the health warnings for humans and animals, and how to perform a basic inspection. We will also highlight how our services can assist with identification and confirmation.

Visual Signs: Nests, Caterpillars, and Defoliation

One of the first indicators of an OPM infestation is the presence of nests and caterpillars on your trees.

  • Nests: OPM nests are typically found on the trunks and branches of oak trees. These nests are white, silky structures that can be the size of a tennis ball or larger. They are often positioned high up in the tree, making them difficult to spot without careful inspection.
  • Caterpillars: The caterpillars are about 2-3 cm long, with distinctive long white hairs and dark bodies marked by a line of orange spots. They often move in a procession, nose-to-tail, which is a characteristic behaviour that gives them their name.
  • Defoliation: Significant feeding by OPM caterpillars can lead to noticeable defoliation of the tree, where large sections of leaves are missing, causing the tree to look sparse and unhealthy.
Oak processionary moth caterpillars © Forestry Commission

Symptoms in Trees: Damage to Foliage and Tree Health

OPM infestations can severely impact the health of your trees.

  • Leaf Damage: The caterpillars feed on the leaves of oak trees, stripping them bare and causing extensive damage. This defoliation weakens the tree, reducing its ability to photosynthesise and produce energy.
  • Stress on Trees: Repeated defoliation over several years can stress the trees, making them more susceptible to other pests and diseases. This can lead to a decline in the overall health of the tree and, in severe cases, death.

Health Warnings: Human and Animal Symptoms from Contact with OPM

OPM caterpillars pose health risks to both humans and animals.

  • Human Symptoms: Contact with the caterpillar’s toxic hairs can cause skin rashes, eye irritation, sore throats, and breathing difficulties. These symptoms can be particularly severe for individuals with pre-existing respiratory conditions or allergies.
  • Animal Symptoms: Pets and livestock can also be affected. Symptoms in animals include excessive drooling, difficulty swallowing, and respiratory distress. If you suspect your pet has come into contact with OPM, seek veterinary care immediately.

How to Perform a Basic Inspection

Conducting a basic inspection can help you detect OPM early.

  1. Examine the Tree: Look closely at the trunk, branches, and leaves of your oak trees. Use binoculars if necessary to inspect higher branches.
  2. Look for Nests and Caterpillars: Search for the distinctive white nests and the caterpillars moving in procession.
  3. Check for Defoliation: Assess the tree for signs of leaf damage and defoliation.
  4. Wear Protective Clothing: When inspecting, wear gloves and long sleeves to protect yourself from the caterpillar’s toxic hairs.

How Our Services Can Help with Identification and Confirmation

At Green Canopy Tree Consultancy, we offer professional services to help you manage OPM infestations.

  • Expert Inspections: Our team conducts thorough inspections to identify OPM infestations. We use specialised equipment and techniques to locate nests and assess the severity of the infestation.
  • Safe Removal: We provide safe and effective removal of OPM nests and caterpillars. Our methods ensure the safety of our team and the public while effectively managing the infestation.
  • Preventive Measures: We offer guidance on preventive measures to reduce the risk of future infestations, including monitoring and early detection strategies.

Stay Vigilant and Protect Your Trees

Identifying and addressing Oak Processionary Moth infestations early is crucial for the health of your trees and the safety of your community. By knowing what to look for and how to respond, you can protect your environment effectively.

Next, we’ll explore the health risks associated with Oak Processionary Moths in more detail. Stay tuned to learn about the potential impacts on humans and animals and how to protect yourself and your loved ones. If you need expert advice or assistance, contact Green Canopy Tree Consultancy today for professional support.


References:

  • Forestry Commission. “Oak Processionary Moth.” Read more
  • Royal Horticultural Society. “Oak Processionary Moth.” Learn more
Cluster of Oak Processionary Moth caterpillars on tree bark with the text 'Combating Oak Processionary Moths: Protecting Our Trees'.

Article Series

Understanding Oak Processionary Moths (OPM)

Oak Processionary Moths (OPM) are a significant concern for tree health and public safety. Understanding these pests is crucial for maintaining the health of our trees and protecting our communities. This article will introduce OPM, explain their life cycle, discuss...

read more
Understanding Oak Processionary Moths (OPM)

Understanding Oak Processionary Moths (OPM)

Oak Processionary Moths (OPM) are a significant concern for tree health and public safety. Understanding these pests is crucial for maintaining the health of our trees and protecting our communities. This article will introduce OPM, explain their life cycle, discuss...

read more

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