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