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

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Ash > Trunk > Holes in trunk or branches

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  • Image: Ash bark beetles, bark holes up close
  • Image: Ash bark beetles, bark hole tunnels
  • Image: Ash bark beetles, bark holes with scale

Ash bark beetles

  • Exit holes first appear in May in trunks and branches
  • Exit holes are 1/8 inch wide and round
  • Galleries cut across the grain in sapwood; typically with two arms starting from a central chamber
  • Adults are 1/8 inch long and brown
  • Larvae are small, about 1/8 inch long, brown head, whitish body, lacks legs; is bent in a C-shape
  • More information on Ash bark beetles...
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  • Image: Clearwing borers, bark holes on trunk
  • Image: Clearwing borers, exit hole up close
  • Image: Clearwing borers, larva in wood

Clearwing borers
Ash borer and banded ash clearwing

  • Exit holes first appear in June and July
  • Exit holes are round and 1/4 inch wide; frass (sawdust and excrement) can be conspicuous underneath
  • Galleries occur deep in sapwood
  • Pupae stick out of exit hole, empty pupal cases are commonly observed after moths have emerged
  • Adults are wasp-like, lacking scales on most of their wings
  • Larvae are caterpillars; have brown head and cream-colored body; up to 1 1/3 inch long
  • More information on Clearwing borers...
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  • Image: Redheaded ash borer, exit hole in bark 1
  • Image: Redheaded ash borer, exit hole in bark 2
  • Image: Redheaded ash borer, tunnels in wood

Redheaded ash borer

  • Exit holes first appear in June
  • Exit holes are round and 3/8 inch wide
  • Galleries start in phloem and eventually enter into sapwood; generally not very serpentine
  • Adults are 1/2 to 5/8 inch long; reddish brown with four yellow bands across their wing covers
  • Larvae are up to 4/5 inch long, whitish, cylindrical; area behind head enlarged and round, head generally inconspicuous; legless
  • More information on Redheaded ash borer...
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  • Image: Flatheaded borers, exit hole in wood

Flatheaded borers
Primarily Chrysobothris sexsignata

  • Exit holes first appear in May and June
  • Found nearly always in black ash
  • Exit holes are oval shaped and 3/16 inch wide
  • Galleries start in phloem and eventually enter into sapwood; generally not very serpentine
  • Adults are 1/2 inch long, bullet-shaped, and bronzed colored
  • Larvae are whitish, flattened, up to 1 inch long; area behind enlarged and flattened; head generally inconspicuous; legless
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  • Image: Woodpeckers, bark removed
  • Image: Woodpeckers, bark up close

Woodpeckers

  • Holes are roundish 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
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  • Image: Carpenterworms, exit hole in bark
  • Image: Carpenterworms, exit hole in wood
  • Image: Carpenterworms, larva

Carpenterworms

  • Exit holes are round and large, about 1/2 inches
  • Galleries starting in sapwood eventually entering heartwood
  • Large amount of sawdust often present at base of ash
  • Heavily infested ash can become gnarled and misshapen
  • 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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  • Image:Emerald ash borer holes
  • Image: Emerald ash borer holes
  • Image: Emerald ash borer holes

Emerald ash borers

  • Chewing damage caused by adults occurs late May to early August
  • Create D-shaped exit hole
  • Slender bodied, 1/3 to 1/2 inch long; iridescent green with coppery colored head
  • More information on Emerald ash borers...

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