Lackey moth

Malacosoma neustria

1. Identification

• Common name: Lackey moth
• Scientific name: Malacosoma neustria L.
• Order: Lepidoptera
• Family: Lasiocampidae

2. Pest description

• Caterpillars bluish to brownish in colour, with light and dark longitudinal lines, reaching 40–45 mm.
• Adults light-brown in colour, with a 25–35 mm wingspan, rounded wings and a simple pattern.
• Gregarious caterpillars, forming dense silken nests on the branches.
• Defoliating species, with periodic population outbreaks.

3. Main hosts

• Apple tree.
• Pear, plum, cherry and other fruit trees.
• Oak, chestnut and various wild broadleaf trees.

4. Symptoms and damage

• Intense defoliation due to caterpillar feeding, especially in spring.
• Presence of bulky silken nests on the branches.
• Reduced tree vigour and decreased production.
• More severe damage in young or poorly monitored orchards.

5. Biological cycle

• Eggs deposited in compact rings around the branches in summer.
• Caterpillars hatch in early spring and feed in groups.
• Formation of silken nests where they remain during part of their development.
• Pupation in silken cocoons attached to the vegetation.
• Adults emerge in summer, completing the annual cycle.

6. Monitoring

• Observation of egg rings on the branches during winter.
• Detection of silken nests and caterpillars in early spring.
• Assessment of defoliation intensity.
• Monitoring of outbreaks in orchards and forest areas.

7. Management measures

• Cultural: manual removal of egg rings in winter and destruction of silken nests.
• Preventive: regular monitoring of orchards and susceptible broadleaf trees.
• Biological: application of Bacillus thuringiensis during the early caterpillar stages.
• Integrated protection: defining intervention thresholds, judicious use of authorised insecticides and coordinated actions in areas with recurrent outbreaks.

Bibliographic references

• CABI – Invasive Species Compendium – Malacosoma neustria.
• EPPO Global Database – Malacosoma neustria.
• Carter, D. J. (1984). Pest Lepidoptera of Europe. Dr W. Junk Publishers.
• Alford, D. V. (2007). Pest and Disease Management Handbook. Blackwell Publishing.
• Schaffner, U. et al. (2001). Population dynamics of the lackey moth. Agricultural and Forest Entomology, 3, 199–208.