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

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

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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
  • Blue and black with characteristic footprint shaped white markings on top of body
  • Damage occurs May and June
  • More information on Forest tent caterpillars...
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  • Image: Fall webworm 1
  • Image: Fall webworm 2
  • Image: Fall webworm 3

Fall webworm
Hyphantria cunea

  • Produces silken webbing that covers the ends of branches
  • Chews entire sections of leaves, leaving major veins and can defoliate trees in high infestations
  • Yellowish or greenish with long, fine white hairs with two rows of black spots down its back; approx. 1 inch long at maturity
  • Damage occurs from late July through September
  • More information on Fall webworms...
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  • Image: Yellownecked caterpillar 1
  • Image: Yellownecked caterpillar 2
  • Image: Yellownecked caterpillar 3

Yellownecked caterpillar
Datana ministra

  • Young larvae skeletonize leaves, i.e. eat the leaf tissue between the veins so that it appears lace-like, gregariously (in groups)
  • Older larvae eat entire leaves, except the leaf stalk; feed solitary from leaf margins
  • Yellow and black stripes along body with black head; fine white hairs over entire body; head and tail get lifted in typical “U” appearance when distressed
  • Damage seen July into September
  • More information on Yellownecked caterpillars...
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  • Image: Orange-striped oakworm 1
  • Image: Orange-striped oakworm 2
  • Image: Orange-striped oakworm 3

Orange-striped oakworm
Anisota senatoria

  • Young larvae skeletonize leaves, i.e. eat the leaf tissue between the veins so that it appears lace-like, gregariously (in groups)
  • Older larvae usually defoliate one branch at a time, eating entire leaves, except the central vein; less gregarious compared to young larvae
  • Young larvae greenish-yellow, older larvae are black with orange; 2 “horns” just behind the head; two inches when fully grown
  • Feeding during late July, August, and into September
  • White oak species is a preferred host
  • More information on Orange-striped oakworm...
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  • Image: Redhumped oakworm 1
  • Image: Redhumped oakworm 2

Redhumped oakworm
Symmerista canicosta

  • Larvae eat leaves and can defoliate branch
  • Light colored body with red head with orange-red hump near back end; approx. 1 ¾ inch long
  • Damage common in late summer
  • White and bur oak are preferred hosts
  • More information on Redhumped oakworm...
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  • Image: June beetle 1
  • Image: June beetle 2
  • Image: June beetle 3

June beetle
Phyllophaga spp.

  • Adults eat leaves, preferring young, tender leaves
  • Chocolate brown to black; ½ to 1 inch long, oblong; shiny, hard bodies; last several segments of antennae asymmetrical and comb-like
  • Active May into July
  • More information on June beetle...
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  • Image: Walkingstick 1
  • Image: Walkingstick 2
  • Image: Walkingstick 3

Walkingstick
Diapheromera femorata

  • Eat leaves; can defoliate trees
  • Wingless, stick-looking insects with long thin legs and antenna; grows up to 3 inches long; color ranges from brown to green
  • Damage seen in late July and August
  • More information on Walkingstick...
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  • Image: Oak webworm 1
  • Image: Oak webworm 2

Oak webworm
Archips fervidanus

  • Hide inside rolled leaves which fill with frass and leaf pieces
  • Larvae eat leaves and can defoliate branches
  • Up to 1 inch long; black head and yellowish to dark green body
  • Black and red oak are preferred hosts
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  • Image: Gypsy moth 1
  • Image: Gypsy moth 2
  • Image: Gypsy moth 3

Gypsy moth
Lymantria dispar

  • Chew leaves and can defoliate entire trees
  • Mature larvae are 2 inches long; upper side has five pairs of blue dots near front of body followed by six pairs of red dots down the back
  • Damage occurs in June and July
  • Is currently a federally quarantined pest in Minnesota; not established in Minnesota; if found, call Minnesota Dept. of Agriculture at 651-201-6684 or 1-888-545-6684
  • More information on Gypsy moth...

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