Most Unwanted: Emerald Ash Borer

How to spot Emerald Ash Borer (Agrilus planipennis)


  • The adult beetles emerge from mid-May to late-July
  • They have metallic green bodies – beetles in this family are known as 'jewel beetles' because of their bright colours – and are 7.5-13.5mm long
  • Burrowing larvae in the bark create larval galleries. The tunnels typically created by these larvae meander and bend sharply
  • They cause initial thinning and yellowing of foliage, which can be general or limited to certain branches
  • Fissures (narrow cracks) form in the bark, caused by growth of scar tissues
  • D-shaped holes (about 3mm in diameter), are produced in the trunk by adults emerging from tunnels
  • Unlike other beetles in its family, the Emerald Ash Borer can attack healthy trees and cause their death.

Plants affected:

  • Ash trees
  • Small trees can be killed in a year, but larger trees can take up to four years to die.

UK status and other information:

  • Although there is no evidence to date that the Emerald Ash Borer is present in the UK, the increase in the global movement of wood and wood packaging poses a significant risk of its accidental introduction
  • Native to Far East Asia, the Emerald Ash Borer was confirmed as established in Moscow, Russia, in 2007 and is spreading westwards
  • Its arrival in the UK would be a cause for great concern. It has killed many of the Ash trees in some parts of the USA since its discovery there in 2002.

Why will any findings be important?

  • Should it arrive in the UK, early detection will give us the best chance of control
  • Ash makes up nearly 15% of all broadleaved woodlands in the UK and is a distinctive part of our landscape, as well as having many economic uses such as furniture-making and flooring
  • The Emerald Ash Borer has the potential to devastate our populations of Ash.

Useful links:


Images: beetle © Forestry Commission, larval galleries ©Edward Czerwinski, holes © Debbie Miller