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

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

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  • Image: Spiny elm caterpillar 1
  • Image: Spiny elm caterpillar 2
  • Image: Spiny elm caterpillar 3

Spiny elm caterpillar (Mourning cloak butterfly)
Nymphalis antiopa

  • Larvae feed in groups, eating leaves; they can defoliate branches
  • Black with scattered white spots with a single row of red spots and black spines along its body
  • Turn into mourning cloak butterflies
  • Larvae feed in May and June and again in July or August by a second generation
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  • Image: Cankerworms 1
  • Image: Cankerworms 2
  • Image: Cankerworms 3

Cankerworms
Alsophila pometaria (fall) and Paleacrita vernata (spring)

  • Larvae chew between the major veins at first, eventually chewing everything except midveins
  • Defoliation typically light to moderate, although it can be severe
  • Smooth-bodied, light green to brown, 2 inches long when fully grown; moves in characteristic looping motion
  • Damage occurs late April/early May until June
  • More information on Cankerworms...
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  • Image: Forest tent caterpillar 1
  • Image: Forest tent caterpillar 2
  • Image: Forest tent caterpillar 3

Forest tent caterpillar
Malacosoma disstria

  • Larvae chew 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
  • Damage occurs May and June
  • More information on Forest tent caterpillar...
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  • Image: Whitemarked tussock moth 1
  • Image: Whitemarked tussock moth 2
  • Image: Whitemarked tussock moth 3

Whitemarked tussock moth
Orygia leucostigma

  • Young larvae windowpane feed (i.e. feed on one layer of leaf tissue between veins) giving them a lacelike appearance
  • Older larvae consume entire leaves except the midrib and large veins
  • Caterpillars have a red-orange head with two sets of black tufts near the head; yellowish hairy body with distinct tufts of hair resembling a toothbrush on top of the body
  • Full grown larvae are 1 ¼ inches long
  • Damage by 2 generations, first from May to June and a second one from August to September
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  • Image: Elm leaf beetle 1
  • Image: Elm leaf beetle 2
  • Image: Elm leaf beetle 3

Elm leaf beetle
Pyrrhalta luteola

  • Adults eat small, nearly circular holes in the leaves during spring
  • During late spring larvae windowpane feed, i.e. eat one layer of leaf tissue between the veins leaving the upper leaf surface intact
  • Entire leaf canopy can be affected so may look brown from a distance
  • Adults are ¼ to 3/8 inch long and yellow with black stripes along length of wing covers
  • Larvae up to 1/2 inch long; dull yellow with lateral black stripes
  • Siberian elms are most preferred host followed by American elms
  • More information on Elm leaf beetle...
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  • Image: Elm sawfly 1
  • Image: Elm sawfly 2
  • Image: Elm sawfly 3

Elm sawfly
Cimbex americana

  • Larvae chew on leaf edges, as they mature entire leaves are consumed
  • Full-grown larva is almost wrinkly; 2 inches long; yellowish to greenish with black stripe down its back; several whitish spots giving it a grainy appearance
  • Larvae present in June and feed until late July or August
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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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  • Image: Redhumped caterpillar 1
  • Image: Redhumped caterpillar 2

Redhumped caterpillar
Schizura concinna

  • Larvae eat entire leaves, leaving only the midvein
  • Red head with a wavy black, yellow, and white striped body and a red projection (hump) on the thorax behind the head; 1 1/3 inches long when fully grown
  • Damage occurs in August and September
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  • Image: Elm flea weevil 1
  • Image: Elm flea weevil 2
  • Image: Elm flea weevil 3

Elm flea weevil
Orchestes alni

  • Adults eat on leaf undersides creating small holes in leaves
  • Larvae create blotch mines at tips of leaves
  • Adults are brown with black heads, black spots on wings, long snout, 1/8 inch long
  • Preferred hosts are Siberian and hybrid elms
  • More information on Elm flea weevil...

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