The signs of Infestation

You can identify trees infested by the emerald ash borer by the following signs:
  • Loss of green colour (fading) of the crown of the tree (Figure 1)
  • Small D-shaped larvae exit holes beginning in the month of May (Figures 2 and 3)
  • Proliferation of young shoots on the trunk or branches (Figure 4)
  • Sinuous S-shaped galleries under the bark (Figures 5 and 6)
  • Vertical slots on the trunk
  • Increase in the production of fruit (seed pods)
  • Holes in the leaves (gnawed by the adult)


Figure 1 | Dieback of the crown



Figure 2 | Small D-shaped larvae exit holes after the month of May



Figure 3 | Small D-shaped larvae exit holes and sinuous S-shaped galleries under the bark


Figure 4 | Presence of shoots



Figure 5 | Larva and galleries (Jerry Dowding, CFIA)



Figure 6 | Massively infested ash (CFIA)