Xyleborus

Xyleborus dispar

1. Identification

• Common name: Pear blight beetle
• Scientific name: Xyleborus dispar Fabricius
• Order: Coleoptera
• Family: Curculionidae (Scolytinae)

2. Pest description

• Small bark beetle (c. 2–3 mm), cylindrical body and dark‑brown colouration.
• Females are winged and responsible for colonisation; males are wingless and remain in the galleries.
• It bores galleries into the wood, where it establishes symbiotic fungi that serve as food for the larvae.
• It mainly attacks weakened, recently‑pruned trees or those subject to physiological stress.

3. Main hosts

• Pome fruits: apple, pear, quince.
• Stone fruits: plum, cherry, peach.
• Other broadleaf trees: grapevine, walnut, chestnut, oak and various ornamentals.

4. Symptoms and damage

• Presence of small circular holes in the trunk and branches.
• Expulsion of fine sawdust (“flour”) through the entry holes.
• Drying of branches and reduced plant vigour.
• In severe attacks, progressive decline and death of branches or of the tree.
• Greater incidence in weakened trees or those subject to recent cuts.

5. Biological cycle

• Females emerge in spring and seek fresh or weakened wood to start the gallery.
• Eggs laid inside the galleries; larvae feed on symbiotic fungi.
• Protected development within the wood.
• Normally 1 generation per year, with more possible in mild climates.
• Overwinters mainly as an adult inside the galleries.

6. Monitoring

• Direct observation of holes and sawdust expulsion.
• Inspection of recently pruned branches or weakened trees.
• Ethanol traps as a complementary detection method.
• Reinforced monitoring in late winter and early spring.

7. Management measures

• Cultural: removal and destruction of attacked branches; avoid severe pruning during flight periods; reinforcement of tree vitality.
• Preventive: avoid water stress; disinfection of pruning tools; avoid leaving cut wood in the orchard.
• Biological: promotion of natural enemies present in the ecosystem.
• Integrated protection: judicious application of authorised products when indicated; integration with cultural prevention practices.

Bibliographic references

• EPPO Global Database – Xyleborus dispar.
• CABI – Invasive Species Compendium – Xyleborus dispar.
• Faccoli, M. (2008). Host preference and host colonization of Xyleborus dispar. Journal of Pest Science.
• Kirkendall, L. R. et al. (2015). Scolytinae biology and host interactions. Annual Review of Entomology.