Golden twin-spot moth

Thysanoplusia orichalcea

1. Identification

• Common name: Slender burnished brass moth; Golden twin-spot moth
• Scientific name: Thysanoplusia orichalcea Fabricius
• Order: Lepidoptera
• Family: Noctuidae

2. Pest description

• Caterpillars of a bright green colour, narrow and elongated body, with light longitudinal lines; they move with a typical “looping” motion.
• Adults with golden-brown forewings, with a characteristic metallic sheen; greyish hindwings.
• Polyphagous species, attacking various vegetable and ornamental crops.
• Caterpillars feed on leaves, causing perforations and partial or total defoliation.
• It may have several generations per year in warm climates.

3. Main hosts

• Vegetable crops (tomato, bean, cabbage, lettuce).
• Oilseeds (soybean).
• Various ornamental plants.
• Spontaneous species that act as a reservoir.

4. Symptoms and damage

• Irregular perforations on the leaves, especially between the veins.
• Partial defoliation in moderate attacks; severe defoliation in high populations.
• Damage to young leaves and tender shoots.
• Reduction of plant vigour and productivity.
• Presence of caterpillars and droppings on the underside of the leaves.

5. Biological cycle

• Eggs laid singly or in small groups on the surface of the leaves.
• Caterpillars go through several instars, feeding intensively.
• Pupation generally occurs on the plant, inside a silken cocoon.
• Adults active mainly at dusk and during the night.
• Number of generations depending on temperature, which may be high in warm regions.

6. Monitoring

• Direct observation of caterpillars and foliar damage.
• Search for eggs and young caterpillars on the underside of the leaves.
• Light traps to detect adults.
• Regular sampling in sensitive crops during periods of greater risk.

7. Management measures

• Cultural: removal of infested plants; control of spontaneous host plants; crop rotation.
• Preventive: frequent monitoring; avoid excess nitrogen fertilisation that favours vegetative growth.
• Biological: promotion of natural parasitoids and predators; application of Bacillus thuringiensis at young stages.
• Integrated protection: judicious application of authorised insecticides when intervention thresholds are reached; integration of cultural, biological and chemical measures.

Bibliographic references

• EPPO Global Database – Thysanoplusia orichalcea.
• CABI – Invasive Species Compendium – Thysanoplusia orichalcea.
• Robinson, G. S. et al. (2010). Hostplants of the moths of the world. Natural History Museum.
• Hill, D. S. (1987). Agricultural Insect Pests of the Tropics and their Control. Cambridge University Press.