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Elm Bark Beetle (European and Native)

CharacteristicsCut away section of elm tree showing elm beetle larvae

  • Eggs Females construct their egg-laying galleries in dying or recently killed trees. The galleries extend across the grain of wood of an elm tree.
  • Adults The European elm bark beetle is very small, only 3 millimetres long and has a shiny, reddish brown body. The native elm bark beetle is slightly smaller and has a dull, rough brown body. The native elm bark beetle can over winter in the bark of a tree (trunk or large branches). Adults begin to appear in May and feed in the canopy of the tree. Both adult bark beetle species can fly from elm tree to elm tree within a few hundred metres. Often they carry a fungus called Dutch elm disease (Ceratocystis ulmi or Opistoma ulmi) which infects elm trees as the beetle feeds. The fungus eventually kills the tree.

Identifying infestations

  • Red ‘sawdust’ at the bottom of your elm tree Elm bark beetles may leave rInitial stage of DED - wilting leavesed ‘sawdust’ or frass at the base of a tree in the fall and early spring.
  • Wilting or dying elm leaves  The elm tree’s leaves will wilt if it is infected with Dutch elm disease. The leaves may be yellow (if spring or summer) or the leaves may turn brown and not fall off (if it is later summer or fall.)

IPM Toolkit

  • Preventive tools
    • Do NOT bring firewood from campsites or cabins into Regina where beetles may reside.
    • Do NOT prune between April 1 and August 31 each year. Provincial legislation prohibits pruning during this period because the sap scent from a fresh cut attracts the elm bark beetle.
  • Physical tools
    • When pruning is allowed, remove dead or broken branches from your private elm trees. Sterilize your pruning equipment with methanol (gasline antifreeze) between cuts. Immediately dispose of any pruned wood by taking it to the landfill. Note: You are not allowed to prune City-owned trees.
  • Biological tools
    • Not applicable
  • Least toxic chemical tools
    • Hire a licensed applicator apply a basal spray to your private elm tree in the fall. Note: You are not allowed to spray City-owned trees; the City will spray if it is required as part of their Dutch Elm Disease Control Program.