Emerald pink weevil

Cneorhinus serranoi

1. Identification

• Common name: Emerald rose-coloured weevil
• Scientific name: Cneorhinus serranoi Gómez & Sánchez‑Ruiz
• Order: Coleoptera
• Family: Curculionidae

2. Pest description

• Adults: Weevils of 4–6 mm; robust body, pinkish to greenish colouration with metallic reflections; coating of fine scales giving the “emerald” appearance; short rostrum; geniculate antennae typical of weevils.
• Larvae: Apodous, whitish, curved body, brown head; develop in the soil feeding on young roots.
• Pupae: Formed in the soil, in small earthen chambers.
• Eggs: Laid in the soil or at the base of host plants.

3. Main hosts

• Mediterranean shrubs, especially Cistus spp. and Halimium spp.
• Woody aromatic plants such as Lavandula spp., Rosmarinus officinalis and Thymus spp..
• Garden and nursery ornamentals, including Viburnum, Photinia, Pittosporum and Euonymus.
• Native shrubs such as Arbutus unedo, Myrtus communis and Pistacia lentiscus.

4. Symptoms and damage

• Adults feed on the leaves, causing semicircular notches on the margins.
• Aesthetic foliar damage that may compromise the ornamental value of the plants.
• Larvae feed on the roots, reducing vigour and potentially causing wilting or stunted growth.
• In young plants, intense attacks can lead to death due to the loss of fine roots.
• More severe damage in light and moist soils, favourable to larval development.

5. Biological cycle

• One annual generation, with variations possibly occurring depending on the climate.
• Adults active mainly in spring and early summer.
• Egg-laying in the soil; larvae develop feeding on roots until autumn.
• Larvae overwinter in the soil and pupate the following spring.
• Development favoured by moist soils and mild temperatures.

6. Monitoring

• Observation of semicircular notches on the leaf margins.
• Inspection of the base of the plants for signs of wilting or reduced growth.
• Assessment of the root system in suspect plants.
• Reinforced monitoring in nurseries and areas with a history of the pest.

7. Management measures

• Cultural: Removal of heavily affected plants; improvement of soil drainage; avoiding excessive watering.
• Preventive: Use of clean substrates in nurseries; inspection of acquired plants; avoiding the introduction of contaminated soil.
• Integrated protection: Intervention only when necessary; practices that reduce excessive moisture; regular monitoring in young and ornamental plants.

Bibliographic references

• EPPO Global Database – Cneorhinus serranoi.
• Gómez, J. & Sánchez‑Ruiz, M. (2005). Description and distribution of Cneorhinus serranoi.
• CABI datasheets on Curculionidae (general references for the group).