Tree Killers: Emerald Ash Borer

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  • Common English name: Emerald Ash Borer
  • Other names: “EAB”
  • Latin (scientific) name: Agrilus planipennis

Threat type

150x150 insects

History in Canada

  • the beetle was introduced to North America from China probably in the 1990’s but was not discovered until 2002 when it was found in Michigan and southwest Ontario in Essex County
  • since then it has been found in Ohio, Maryland, Virginia, Indiana, Illinois, and Pennsylvania


  • adult beetles are shiny green and 8-13 mm long (1/2 in)
  • mature larvae are whitish and 26-32 mm (1-1 ¼ in)
  • adults generally emerge in spring and summer and lay eggs during this period
  • the beetle requires one or two years to develop from egg to adult
  • adults and larvae can travel on firewood and nursery stock
  • larvae tunnel under the outer bark and create serpentine feeding ‘galleries’
  • infected trees show yellowing and loss of leaves in the canopy, and suckers growing from the base of the trunk
  • gradually, the damage spreads to the rest of the tree which eventually dies
  • suckers that resprout from the base can live for several years

Impact on Trees

  • able to attack and kill healthy trees
  • all native and introduced ash trees are susceptible
  • ash trees are very widely planted
  • the larvae consume the inner bark which strangles the tree
  • infected trees die within one or two years
  • southwestern Ontario from Windsor to London has been severely affected by the beetle where hundreds of thousands of ash trees have been killed

What can be done to control this tree killer?

  • In 2013, Tree Canada launched #OperationReLeaf: Emerald Ash Borer in an attempt to fight the spread of this tree killer.
  • the beetles are very difficult to kill
  • the larvae feed under the bark and the adult’s exit holes are very small making infestations difficult to detect early
  • the main strategy has been to remove and destroy all ash trees in the area of an infestation and prohibit movement of any ash trees or firewood from the infested area
  • a pilot study is underway involving a parasitic wasp

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