Raspberry beetle

Byturus spp.

1. Identification

• Common name: Raspberry beetle
• Scientific name: Byturus tomentosus De Geer, Byturus ochraceus Scriba, Byturus unicolor Say, Byturus affinis Crotch
• Order: Coleoptera
• Family: Byturidae

2. Pest description

• Adults: Beetles of 3–4 mm; oval body, yellowish-brown to dark brown; pubescent surface; activity most intense in spring.
• Larvae: Elongated, whitish to yellowish, with a brown head and small bristles; develop inside the fruits.
• Pupae: Formed in the soil, after the mature larvae drop.
• Eggs: Laid on the flowers or directly on the young fruits.

3. Main hosts

• Raspberry as the main host.
• Blackberry and other species of the genus Rubus.
• Some species may also occur on strawberry, although with less impact.

4. Symptoms and damage

• Larvae inside the fruits, reducing commercial quality.
• Borings and damage to the flowers caused by the adults.
• Deformed fruits, with irregular ripening or premature drop.
• Contamination of the fruits by larvae, decreasing market value.
• Reduction in yield in severe infestations.

5. Biological cycle

• One generation per year in most regions.
• Adults emerge in spring and feed on the flowers.
• Egg-laying on the flowers or young fruits; larvae develop inside the fruits.
• Mature larvae fall to the ground for pupation.
• Adults overwinter in the soil or in the leaf litter.
• Development favoured by mild springs and high flower availability.

6. Monitoring

• Observation of damage to the flowers during flowering.
• Inspection of young fruits to detect larvae.
• Shaking branches over a light-coloured surface to assess the presence of adults.
• Chromotropic traps (preferably white or yellow as an alternative) for reinforced monitoring in plots with a history of the pest.

7. Management measures

• Cultural: Removal of infested fruits; cleaning of the leaf litter; improvement of air circulation in the orchard.
• Preventive: Planting in well-drained sites; avoiding excessive vegetative vigour.
• Integrated protection: Intervention only when population levels justify it; preference for selective methods compatible with beneficial organisms; regular monitoring during flowering.

Bibliographic references

• CABI Invasive Species Compendium – Byturus tomentosus.
• EPPO Global Database – Byturus spp.
• Cross, J. V. (1996). Biology and management of raspberry beetle.
• McGregor, R. (1992). Pests of cane fruits.