Bronze bug

Thaumastocoris peregrinus

1. Identification

• Common name: Bronze bug
• Scientific name: Thaumastocoris peregrinus Carpintero & Dellapé
• Order: Hemiptera
• Family: Thaumastocoridae

2. Pest description

• Small adults (2–3 mm), flattened body and light brown coloration.
• Nymphs of yellowish to brownish coloration, very mobile.
• Piercing-sucking mouthpart, feeding on the sap of the leaves.
• More intense activity in hot and dry periods.
• Forms numerous colonies on the underside of the leaves.

3. Main hosts

• Eucalyptus (main host).
• Preference for species such as E. camaldulensis, E. tereticornis and hybrids.
• May occur in plantations, young stands and urban trees.

4. Symptoms and damage

• Progressive bronzing of the leaves, starting from the underside.
• Loss of gloss and appearance of chlorotic spots.
• Drying and premature drop of the leaves.
• Reduction of the growth and vigour of the trees.
• In severe attacks, partial defoliation and significant impact on forest productivity.

5. Biological cycle

• Rapid development in hot climate.
• Eggs laid singly or in small groups on the leaves.
• Nymphs go through several instars before reaching the adult stage.
• Multiple generations per year, with population peaks in summer.
• High dispersal capacity, favouring geographic expansion.

6. Monitoring

• Observation of bronzing of the leaves, especially on the underside.
• Checking for the presence of nymphs and adults in colonies.
• Regular monitoring in young plantations and urban areas with eucalyptus.
• Recording of periods of greatest activity (spring and summer).
• Assessment of the intensity of attack to determine the need for intervention.

7. Management measures

• Cultural: removal of severely affected branches, management of plantation density and promotion of more vigorous trees.
• Biological: use of specific parasitoids, such as Cleruchoides noackae, when present or authorised.
• Integrated protection: continuous monitoring, targeted interventions only when necessary, integration of cultural measures and use of authorised products in a forest or urban context.

Bibliographic references

• EPPO Global Database – Thaumastocoris peregrinus.
• CABI Invasive Species Compendium – T. peregrinus.
• Noack, A. E. et al. (2009). Biology and impact of the bronze bug on eucalyptus.
• Carpintero, D. L. et al. (2006). Description and spread of Thaumastocoris peregrinus.