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

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

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  • Image: Mountain ash sawfly 1
  • Image: Mountain ash sawfly 2
  • Image: Mountain ash sawfly 3

Mountain ash sawfly
Pristiphora geniculata

  • Feed in groups, consuming all of leaf except the mid-vein
  • Larvae defoliate one branch at a time
  • Larvae are ½- ¾ inch long, light greenish yellow with black spots
  • Active from mid-June to early August and again from late August to September
  • More information on Mountain ash sawfly
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  • Image: Japanese beetle 1
  • Image: Japanese beetle 2
  • Image: Japanese beetle 3

Japanese beetle
Popillia japonica

  • Skeletonizes leaves, i.e. chews leaf tissue between the veins creating a lacelike appearance
  • Attacks are common in sunny locations starting at the top of the plant and working down as they feed
  • Adults are metallic green; bronze wings; white tufts of "hair" along their sides
  • Beetles present as early as late June and are active through September
  • More information on Japanese beetle

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