Oak flea beetle

Altica quercetorum

1. Identification

• Common name: Oak flea beetle
• Scientific name: Altica quercetorum Fabricius
• Order: Coleoptera
• Family: Chrysomelidae

2. Pest description

• Small jumping beetle (flea beetle), 3–5 mm.
• Oval, metallic body, blue-green or violet.
• Elongated, dark larvae feed on the underside of the leaves.
• Adults make small circular perforations in the leaf blade.
• Defoliating species typical of oak woodlands.

3. Main hosts

• Pedunculate oak.
• Sessile oak.
• Portuguese oak.
• Other species of Quercus spp..

4. Symptoms and damage

• Circular perforations in the leaves (“shot-hole”).
• Consumption of the leaf blade by the larvae, leaving only fine veins.
• Partial or severe defoliation in intense attacks.
• Reduction of vigour and annual growth.
• Greater susceptibility to other pests and diseases in weakened trees.

5. Biological cycle

• One to two generations per year.
• Adults emerge in spring and feed on young leaves.
• Oviposition on the underside of the leaves.
• Larvae develop during spring and early summer.
• Pupation in the soil or in the leaf litter.
• Adults overwinter in natural shelters.

6. Monitoring

• Observation of circular perforations in young leaves.
• Checking for larvae on the underside of the leaves.
• Assessment of the intensity of defoliation.
• Monitoring in young or weakened oak woodlands.
• Recording of population evolution throughout the spring.

7. Management measures

• Cultural: promotion of tree vigour, removal of heavily attacked material and proper vegetation management.
• Biological: conservation of natural predators such as ladybirds and lacewings.
• Integrated protection: regular monitoring, interventions only when justified and judicious application of authorised products.

Bibliographic references

• EPPO Global Database – Altica quercetorum.
• CABI Invasive Species Compendium – A. quercetorum.
• ICNF – Technical reports on foliar pests of Quercus (2019–2023).
• DGAV – Operational Programme for Forest Health (POSF) (2019).
• DGAV – National Action Plan for the Control of Forest Pests and Diseases (2019).
• Jolivet, P. (1998). Chrysomelidae biology: leaf beetles of forest trees.