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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Elm > Holes in trunk or branches

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Elm > Trunk/Branches > Holes in trunk or branches

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  • Image: Native elm bark beetle 1
  • Image: Native elm bark beetle 2
  • Image: Native elm bark beetle 3

Native elm bark beetle
Hylurgopinus rufipes

  • Egg galleries extend against grain, noticeable when bark is removed
  • Little or no damage to tree unless beetle is carrying Dutch elm disease fungal spores
  • Adults are 3/32 inch long; brownish black
  • All elm species in Minnesota are attacked
  • More information on Native elm bark beetle...
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  • Image: European elm bark beetle 1
  • Image: European elm bark beetle 2
  • Image: European elm bark beetle 3

European elm bark beetle
Scolytus multistriatus

  • Feed at the twig crotches, girdle the bark, cause small branches to fall off
  • Egg galleries extend with the grain, noticeable when bark is removed
  • Little or no damage to tree unless beetle is carrying Dutch elm disease fungal spores
  • Adults are 1/8 inch long; shiny, dark reddish brown to black
  • All elm species in Minnesota are attacked
  • More information on European elm bark beetle...
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  • Image: Woodpeckers 1
  • Image: Woodpeckers 2
  • Image: Woodpeckers 3

Woodpeckers

  • Holes are round and range in size from 1/4 to 1/2 inch
  • Larger holes, 1 1/2 or more inches may be nesting holes and suggest softer heartwood inside the tree
  • Bark often removed around holes
  • Woodpecker probing may indicate presence of wood boring insects under bark
  • Repetitive tapping or drumming heard
  • Birds of varying black and white patterns, often with some red, seen tapping on trees
  • More information on Woodpeckers...
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  • Image: Carpenterworms 1
  • Image: Carpenterworms 2
  • Image: Carpenterworms 3

Carpenterworms
Prionoxystus robiniae

  • Exit holes in wood are round and large, about 1/2 inches
  • Galleries start in sapwood, eventually entering heartwood
  • Large amount of sawdust in piles present at trunk base
  • Stout bodied moths, black and light gray mottled forewings as large as 2 1/2 to 3 inches
  • Yellowish white caterpillars with brown heads; 2 to 3 inches long
  • More information on Carpenterworms...

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