Pine processionary

Thaumetopoea pityocampa

1. Identification

• Common name: Pine processionary moth
• Scientific name: Thaumetopoea pityocampa Denis & Schiffermüller
• Order: Lepidoptera
• Family: Notodontidae

2. Pest description

• Caterpillars with a greyish-brown body and pale lines, covered in urticating hairs.
• They form whitish silky nests in the tree crowns.
• They move in “procession” during winter and early spring.
• Adults are small brownish moths with crepuscular flight.
• A species with a strong forest impact and a risk to people and animals due to its urticating hairs.

3. Main hosts

• Maritime pine.
• Stone pine.
• Scots pine.
• Black pine.
• Cedar as an occasional host.

4. Symptoms and damage

• Intense defoliation, especially in winter.
• Reduced vigour and growth of the trees.
• Greater susceptibility to other pests and diseases.
• High sanitary risk due to the urticating hairs, which cause skin, eye and respiratory irritations.
• Increased danger to domestic animals, especially dogs.

5. Biological cycle

• One generation per year.
• Egg-laying in summer on the needles of the pines.
• Hatching at the end of summer, with nest formation in autumn.
• Caterpillars active during winter.
• Procession for burrowing and pupation at the end of winter or beginning of spring.
• Adults emerge in summer.

6. Monitoring

• Observation of silky nests in the crowns.
• Checking for caterpillars in procession at the end of winter.
• Monitoring with pheromone traps to detect flights.
• Assessment of defoliation intensity.
• Recording of risk zones for people and animals.

7. Management measures

• Cultural: manual removal of nests when possible and safe destruction of the collected material.
• Biological: use of Bacillus thuringiensis at appropriate periods.
• Mechanical: installation of traps collecting the larvae in procession on the trunk.
• Integrated protection: monitoring with pheromones, interventions only when justified, judicious application of authorised products and proper management of risk areas.

Bibliographic references

• EPPO Global Database – Thaumetopoea pityocampa.
• CABI Invasive Species Compendium – T. pityocampa.
• DGAV – Forest Health Operational Programme (POSF) (2019).
• DGAV – National Action Plan for the Control of Forest Pests and Diseases (2019).
• ICNF – Action Plan for the Pine Processionary Moth (2018).
• ICNF – Monitoring reports on the processionary moth (2019–2023).
• Branco, M. et al. (2011). Ecology and management of the pine processionary moth.