Oriental beetle

Exomala (=Anomala) orientalis

1. Identification

• Common name: Oriental beetle
• Scientific name: Exomala orientalis Waterhouse 
• Synonym: Anomala orientalis Waterhouse
• Order: Coleoptera
• Family: Scarabaeidae

2. Pest description

• Adults: Beetles of 8–12 mm; yellowish-brown to dark-brown body; smooth and glossy elytra; activity mainly at dusk and during the night.
• Larvae: “C”-shaped, whitish, with a brown head; typical beetle larvae; develop in the soil feeding on roots.
• Pupae: Formed in the soil, yellowish to brown in colour.
• Eggs: Laid in the soil, preferably in moist areas with dense vegetation.

3. Main hosts

• Agricultural crops: maize, potato, strawberry, grapevine, raspberry, bean.
• Ornamentals and trees: roses, lindens, birches, oaks.
• Lawns and meadows: larvae feed on the roots of grasses, causing significant damage.

4. Symptoms and damage

• Adults feed on the leaves, leaving irregular perforations.
• Damage to flowers and fruits, reducing their commercial value.
• Larvae cause root damage, leading to yellowish patches and drying in lawns and pastures.
• Plants with reduced vigour, greater susceptibility to water stress and possible death in intense attacks.
• In horticultural crops, it can cause significant losses due to the feeding of the larvae on the roots.

5. Biological cycle

• One annual generation in most regions.
• Adults emerge in summer and feed for several weeks.
• Egg-laying in the soil; larvae develop feeding on roots until autumn.
• Larvae overwinter in the soil and resume activity in spring.
• Pupation in late spring, with adults emerging in early summer.
• Development favoured by moist soils, mild temperatures and a high availability of hosts.

6. Monitoring

• Observation of foliar damage and irregular perforations.
• Inspection of lawns to detect larvae (yellowish patches, turf that lifts easily).
• Assessment of plants with symptoms of root stress.
• Light traps may help in the detection of adults.
• Reinforced monitoring in areas with a history of the pest.

7. Management measures

• Cultural: Maintenance of healthy lawns; reduction of excessive irrigation; manual removal of adults in small areas.
• Preventive: Avoiding the transport of soil or plants from infested areas; regular phytosanitary surveillance.
• Integrated protection: Intervention only when necessary; practices that reduce the attractiveness of the habitat; continuous monitoring in sensitive areas.

Bibliographic references

• CABI Invasive Species Compendium – Exomala orientalis.
• EPPO Global Database – Anomala orientalis.
• Potter, D. A. (1998). Destructive turfgrass insects: biology, diagnosis, and control.
• Klein, M. G. (1993). Oriental beetle biology and management.