Japanese pine moth

Dendrolimus superans

1. Identification

• Common name: Japanese hemlock moth
• Scientific name: Dendrolimus superans Butler
• Order: Lepidoptera
• Family: Lasiocampidae

2. Pest description

• Robust caterpillars, with colour varying between greyish-brown and black, displaying tufts of hairs and light longitudinal lines.
• Adults with brown wings, with wavy and subtle patterns; females larger than males.
• Defoliating species with a major impact on conifers, especially in cold and temperate regions of Asia.
• Caterpillars feed intensively on the needles, potentially causing severe defoliation and decline in tree vigour.
• Populations can reach epidemic levels, causing extensive damage in conifer forests.

3. Main hosts

• Abies spp..
• Picea spp..
• Larix spp..
• Pinus spp..
• Other conifers susceptible to a lesser degree.

4. Symptoms and damage

• Partial or total defoliation of the crowns.
• Needles gnawed or completely consumed.
• Dry branches and loss of tree vigour.
• Increased susceptibility to other pests and pathogens.
• Tree mortality in severe and prolonged attacks.

5. Biological cycle

• Eggs laid in masses on the bark or on the needles.
• Caterpillars develop through several instars, possibly overwintering depending on the region.
• Pupation occurs in silky cocoons attached to vegetation or in the soil.
• Adults emerge in summer, with flight concentrated in warm periods.
• Generally one generation per year, which may vary with the climate.

6. Monitoring

• Direct observation of egg masses and caterpillars.
• Assessment of defoliation in conifer stands.
• Light traps for the detection of adults.
• Annual monitoring in at-risk areas or those with a history of outbreaks.

7. Management measures

• Cultural: removal of severely weakened trees; forest management that promotes diversity and resilience.
• Preventive: regular monitoring in conifer stands; early detection of outbreaks.
• Biological: application of Bacillus thuringiensis on young caterpillars; promotion of natural enemies.
• Integrated Protection: judicious application of authorized insecticides when intervention thresholds are reached; integration of cultural, biological and chemical measures.

Bibliographic references

• EPPO Global Database – Dendrolimus superans.
• CABI – Invasive Species Compendium – Dendrolimus superans.
• Schwenke, W. (1978). Die Forstschädlinge Europas. Paul Parey Verlag.
• Ponomarev, V. et al. (2012). Forest defoliators of Northern Asia. Russian Academy of Sciences.