Engraver beetle

Ips acuminatus

1. Identification

• Common name: Engraver beetle
• Scientific name: Ips acuminatus Gyllenhal
• Order: Coleoptera
• Family: Curculionidae (subfamily Scolytinae)

2. Pest description

• Adults: Scolytids of 2.5–4 mm; cylindrical dark-brown body; elytral declivity with four teeth on each side, the upper one being the most developed; smaller and more slender than other species of the genus Ips.
• Larvae: Apodous, whitish, with a curved body and brown head; develop in galleries beneath the bark.
• Pupae: Whitish, formed in pupal chambers inside the bark.
• Galleries: Typical system with a short nuptial gallery and fine, numerous radial larval galleries.

3. Main hosts

• Pines, especially Pinus sylvestris, Pinus nigra and Pinus pinaster.
• It preferentially attacks thin branches, upper crowns and weakened trees.

4. Symptoms and damage

• Fine perforations in the bark, often on upper branches.
• Expulsion of very fine sawdust, accumulated in bark crevices or at the base of the tree.
• Subcortical galleries that interrupt the flow of sap.
• Drying of upper branches, with downward progression.
• Yellowing and premature fall of the needles.
• In intense attacks, it may contribute to the decline and death of the tree.
• Possible association with pathogenic fungi carried by the adults.

5. Biological cycle

• Two to three annual generations, depending on temperature.
• Adults emerge in spring and begin excavating egg-laying galleries.
• Eggs laid in the nuptial gallery; larvae excavate radial galleries.
• Pupation beneath the bark; new adults emerge and may start new generations.
• Development favoured by hot summers, prolonged droughts and trees subjected to stress.

6. Monitoring

• Observation of fine perforations and the expulsion of sawdust.
• Inspection of upper branches showing yellowing or drying.
• Assessment of galleries beneath the bark on suspect branches.
• Reinforced monitoring after storms, cuts, pruning or drought periods.
• Use of traps with specific pheromones for detection and population tracking.

7. Management measures

• Cultural: Removal and destruction of infested branches; elimination of fallen wood; proper management of forest residues.
• Preventive: Maintaining stand vitality; avoiding wounds to the trunk and branches; reducing water stress.
• Integrated protection: Use of traps with pheromones for monitoring; intervention only when necessary; practices that reduce the availability of attractive wood.

Bibliographic references

• CABI Invasive Species Compendium – Ips acuminatus.
• EPPO Global Database – Ips acuminatus.
• Wermelinger, B. (2004). Ecology and management of bark beetles in European conifer forests.
• Lieutier, F., et al. (2004). Bark and wood boring insects in living trees in Europe.