Pest or disease?

Latin name:
Agrilus planipennis

Host trees:
Most ash species

Present in the UK?

Tree Alert required?

Emerald ash borer is a threat to our ash trees, many of which are already suffering from chalara ash dieback.

This pest is from Eastern Asia but has established outside its native range in the USA and Canada, resulting in large losses of ash trees. The range of this pest is increasing, spreading westerly across Eurasia, meaning it is getting closer to the UK.

Emerald ash borer causes damage to trees during its larval phase and spends most of its life inside the tree, making it difficult to spot. The larvae feed in the tree, disrupting the trees vital water and nutrient transport systems. Symptoms include; leaf loss, branches dying, epicormic growth and larval galleries under the bark. When the adults leave the tree they produce D-shaped exit holes. An infestation is usual fatal, this can be quite rapid and small trees can die within a year. For more information on this pest please see the resources below.