Emerald Ash Borer

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

This pest is from Eastern Asia but has established outside its native range in North America, European Russia and Ukraine, resulting in large losses of ash trees. The pest is 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 inner bark of the tree, disrupting the tree’s vital water and nutrient transport systems. Symptoms of EAB may be difficult to distinguish from damage caused by ash dieback disease. Symptoms of Emerald ash borer infestation usually start at the top of the tree, and include leaf yellowing and loss, branches dying, cracks and splits in the bark, and epicormic growth.  

Signs specific to the Emerald ash borer are the D-shaped exit holes produced by adults when they leave the tree, and the feeding galleries made by the larvae which may be observed when the bark is removed or falls off. An infestation is usually fatal, and mortality can be quite rapid – small trees can die within a year. 

For more information about Emerald ash borer, see the resources below.