Brown-tail moth

Euproctis chrysorrhoea

1. Identification

• Common name: Brown-tail moth
• Scientific name: Euproctis chrysorrhoea L.
• Order: Lepidoptera
• Family: Erebidae

2. Pest description

• Dark-coloured caterpillars, with light longitudinal lines and tufts of urticating hairs, reaching 25–35 mm.
• White adults, with a wingspan of 30–35 mm, displaying a characteristic tuft of brown hairs on the abdomen.
• Defoliating species, with gregarious caterpillars that form silky nests in the trees.
• Urticating hairs may cause skin and respiratory irritation in people and animals.

3. Main hosts

• Oaks.
• Apple, pear, plum and other fruit trees.
• Several spontaneous tree and shrub species.

4. Symptoms and damage

• Partial or total defoliation of the trees due to the feeding of the caterpillars.
• Presence of silky nests at the tips of the branches.
• Reduction of tree vigour and greater susceptibility to other pests and diseases.
• Health risk due to the urticating hairs of the caterpillars.

5. Biological cycle

• Eggs laid in masses covered with brown hairs at the end of summer.
• Caterpillars hatch in autumn and remain in silky nests during the winter.
• Feeding activity intensifies in spring.
• Pupation occurs in silky cocoons attached to the vegetation.
• Adults emerge in summer, completing the annual cycle.

6. Monitoring

• Observation of silky nests on the branches during winter and early spring.
• Counting of egg masses at the end of summer.
• Assessment of the intensity of defoliation.
• Monitoring of foci in urban areas due to the risk to public health.

7. Management measures

• Cultural: removal and destruction of nests during the winter, avoiding the dispersal of urticating hairs.
• Preventive: regular monitoring of sensitive trees and management of the surrounding vegetation.
• Biological: conservation of natural enemies and use of Bacillus thuringiensis on young stages of the caterpillars.
• Integrated protection: definition of intervention thresholds, judicious application of authorised insecticides and coordinated actions in urban and forest areas.

Bibliographic references

• CABI – Invasive Species Compendium – Euproctis chrysorrhoea.
• EPPO Global Database – Euproctis chrysorrhoea.
• Carter, D. J. (1984). Pest Lepidoptera of Europe. Dr W. Junk Publishers.
• Battisti, A. et al. (2011). Health risks associated with urticating caterpillars. Human and Ecological Risk Assessment, 17, 612–626.
• Hoch, G. et al. (2009). Biology and management of the brown‑tail moth. Forest Ecology and Management, 257, 2062–2071.