Almond bark beetle

Scolytus amygdali

1. Identification

• Common name: Almond bark beetle
• Scientific name: Scolytus amygdali Guerin‑Méneville
• Order: Coleoptera
• Family: Curculionidae (subfamily Scolytinae)

2. Pest description

• Adults: Small cylindrical beetles, 2–3 mm, dark brown to black colouring; robust body typical of bark beetles.
• Larvae: Apodous, whitish, body curved in a “C” shape, brown head.
• Pupae: Whitish, developing in pupal chambers inside the bark.
• Galleries: Typical longitudinal and radial galleries excavated in the bark and cambium.

3. Main hosts

• Almond tree as the preferred host.
• It may also attack other species of the genus Prunus, especially weakened trees or those subject to water stress.

4. Symptoms and damage

• Visible borings in the bark, often with the expulsion of fine sawdust.
• Subcortical galleries that interrupt the flow of sap.
• Drying of branches and progressive decline of the crown.
• Greater susceptibility of the tree to secondary infections by fungi.
• In severe attacks, death of branches or even of the tree may occur.

5. Biological cycle

• Several generations per year, depending on temperature.
• Adults emerge in spring and begin excavating egg-laying galleries.
• Eggs deposited in longitudinal galleries; larvae excavate radial galleries.
• Pupation inside the bark.
• Development favoured by weakened trees, water stress or mechanical damage.

6. Monitoring

• Observation of recent borings and expulsion of sawdust.
• Inspection of dry branches or those with symptoms of decline.
• Assessment of galleries under the bark in suspect branches.
• Reinforced monitoring during periods of heat and drought.
• Traps with attractant for early detection of adults.

7. Management measures

• Cultural: Removal and destruction of infested branches; improvement of the tree's vigour conditions; avoid water stress.
• Preventive: Maintenance of good pruning and healing practices; avoid wounds to the bark.
• Integrated protection: Intervention only when necessary; preference for methods that reduce the attractiveness of weakened trees; continuous monitoring in susceptible orchards.

Bibliographic references

• CABI Invasive Species Compendium – Scolytus amygdali.
• Kirkendall, L. R., et al. (2015). Scolytinae biology and host interactions.
• EPPO Global Database – Scolytus amygdali.