Apple tree borers of two species (flathead apple borer, roundhead apple borer) are pests common to apple trees in the United States and Canada and can even be found on other trees such as pear, oak, and hickory.

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Appearance:

  • Round-headed apple tree borers are striped long-horn beetles about 5/8" long.  The larva is a fleshy, cream-colored legless grub with a dark brown head and blackish mandibles.

  • Flat-headed apple tree borer is a dark/brown beetle with a metallic luster that is about 1/2" long.  Grubs are legless with a broad, flattened head end and a cylindrical body.

Damage:

  • The larvae bore into the bark, filling the hole behind them with feces and wood-shaving, and then feed on the tree.

  • The tunnel they create can be 3 inches long or longer.

  • It only takes 1-2 larvae to kill a young tree.

Timing:

  • The adults typically begin laying their eggs under bark scales or in bark crevices on the south and west sides of the main trunk and larger branches.

Treatment:

  • Borers selectively attack weakened trees.  Maintain healthy trees!

  • Wrap window screen around the tree trunk base. This will prevent the borers from having access to the tree bark.

  • Treat the tree with parasitic nematodes.

  • Use preventative bark sprays: pyrethrin or neem

  • Place diatomaceous earth (a naturally occurring soft, sedimentary rock crumbled into a fine powder) around the tree.

For more information about the apple borer, visit this page on Michael Phillips’ (author of “The Holistic Orchard”) website or the website of your local conservation department.

Sources: Michael Phillips, “The Holistic Orchard” and Patrick L. Byers, Horticulture Specialist