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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Ash > Holes in leaves or parts of leaves missing

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Ash > Leaves > Holes in leaves or parts of leaves missing

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  • Image: Blackhead ash sawflies, larvae on leaf 1
  • Image: Blackhead ash sawflies, larvae on leaf 2
  • Image: Blackhead ash sawflies, larvae on leaf 3

Blackhead ash sawflies

  • Occurs May and June
  • Chews leaf tissue starting at tip and working its way back, leaving midveins
  • Defoliation generally light to moderate, although can have potential to be severe
  • Smooth-bodied, black head, white/yellow body; grows to about 3/4 inch long when full grown
  • More information on Blackhead ash sawflies...
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  • Image: Cankerworms, leaf defoliation up close 1
  • Image: Cankerworms, leaf defoliation up close 2
  • Image: Cankerworms, leaf defoliation up close 3

Cankerworms (spring and fall)

  • Occurs late April/early May until June
  • Chews smalls holes between veins at first, later chewing leaf tissue except for major veins, and eventually chewing all of leaves except midvein
  • Defoliation typically light to moderate, although it can potentially be severe
  • Smooth-bodied, light green to brown, 2 inches long when fully grown; moves in characteristic looping motion
  • More information on Cankerworms...
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  • Image: Forest tent caterpillars, defoliated leaf
  • Image: Forest tent caterpillars, larvae on leaf
  • Image: Forest tent caterpillars, larva on bark

Forest tent caterpillars

  • Occurs May and June
  • Chews entire sections of leaves, sometimes leaving some major veins; defoliation often severe
  • Hairs along sides of body, blue and black with characteristic footprint shaped white markings on top of body
  • More information on Forest tent caterpillars...
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  • Image: Cercropia caterpillar 1
  • Image: Cercropia caterpillar 2

Cecropia caterpillars

  • Occurs August and September
  • Chews entire sections of leaves; defoliation typically is minor
  • Light green body with double row of reddish orange knobs on thorax behind head; also series of smaller yellow and blue knobs on abdomen; grows up to 4 inches long
  • Becomes a large, attractive moth
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  • Image: Polyphemus caterpillar 1
  • Image: Polyphemus caterpillar 2

Polyphemus caterpillars

  • Occurs August and September
  • Chews entire sections of leaves; defoliation typically is minor
  • It is pale green with sparse long hairs along top and sides of abdomen; grows up to 3 1/2 inches long
  • Becomes a large, attractive moth
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  • Image: Tiger swallowtail caterpiller

Tiger swallowtail caterpillars

  • Occurs June to September
  • Chews entire sections of leaves; defoliation typically is minor
  • It is light green with a pair of blue, black, and yellow eyespots behind its head; smooth-bodied growing over two inches long
  • Becomes an attractive butterfly
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  • Image: Linden looper, larva 1
  • Image: Linden looper, larva 2

Linden loopers

  • Occurs May and June
  • Chews portions of leaves; defoliation typically is minor
  • Smooth-bodied with reddish brown head, it is patterned black, gray, yellow, with a light colored underside; moves in characteristic looping motion
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  • Image: Emerald ash borer, deloliated leaf 1
  • Image: Emerald ash borer, deloliated leaf 2
  • Image: Emerald ash borer, deloliated leaf 3

Emerald ash borers

  • Chewing damage caused by adults occurs late May to early August
  • Chews along the edges of leaves; defoliation is typically minor
  • Slender bodied, 1/3 - 1/2 inch long; iridescent green with coppery colored head
  • More information on Emerald ash borers...

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