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UK Risk Register Details for Thaumetopoea processionea

This record was last updated on 24/01/2023

Common Names

  • Oak processionary caterpillar
  • Oak processionary moth

Scenario and Pathways

Scenario for Risk Register

  • show / hide
  • Pest spreads to maximum extent

Pathway Assessed for Entry to UK

  • show / hide

Common Pathways

  • show / hide
  • Plants for planting (except seeds bulbs and tubers)
  • Roundwood of oak with bark present

Risk Ratings and Current Mitigations

Unmitigated Risks

Likelihood [1 - 5] 5
Spread [1 - 5] 3
Impact [1 - 5] 4
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 20
UK Relative Risk Rating [1 - 125] 100

Current Mitigations

  • show / hide

Key mitigation for pest

Regulated protected zone quarantine pest (Northern Ireland). Regulated quarantine pest (Great Britain) (known to occur in the country)



Industry Scheme

Contingency Plan



Mitigated Risks

Likelihood [1 - 5] 3
Spread [1 - 5] 2
Impact [1 - 5] 3
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 9
UK Relative Risk Rating [1 - 125] 45

Proposed Actions

Proposed Actions



Management By Industry

Targeted Survey


Contingency Plan



Distribution and Pest Details


Country / Territory Status Notes
Austria Present
Belgium Present
Bulgaria Present
France Present
Germany Present
Italy Present
Netherlands Present
Poland Present
Romania Present
Slovenia Present
Spain Present
Sweden Present
United Kingdom Present (Limited)
Switzerland Present
Russia Present
Belarus Present
Ukraine Present
Moldova Present
Croatia Present
Serbia Present
Türkiye Present

Type of Pest

  • Insect (Lepidoptera)

Host or Industry at Risk

  • show / hide


Major Hosts

  • Quercus L.
  • Quercus calliprinos Webb
  • Quercus cerris L.
  • Quercus petraea (Matt.) Liebl.
  • Quercus pubescens Willd.
  • Quercus pyrenaica Willd.
  • Quercus robur L.
  • Quercus boissieri

Threats to Protected Cultivation

Forest Tree Pests and Pathogens

  • Broadleaved

Further Information

PRA Availability

UK (2007), EFSA (2009)

Regulation and EPPO listing

  • show / hide

Regulated quarantine pest (Great Britain) (known to occur in the country). Regulated protected zone quarantine pest (Northern Ireland)

Actions Indicated

  • show / hide


Surveillance and statutory action against findings in line with legislation.

General Comments

Pest of oak which has both plant and human health impacts. Regulation in place to protect pest free areas. Containment strategy in place to prevent spread from infected sites in London. Stakeholder groups will be a valuable contribution to monitoring.

Risk Records for this Pest