Be on the lookout for a few very destructive pests. Pests are grouped by the pest, or location and type of the symptoms. To learn more about a forest pest, simply "click" on one of the images found below.

• Insects:

Asian Longhorned Beetle	Balsam Woolly Adelgid (Firs Only)	HemlockWoolly Adelgid (Hemlock Only)

• Foliage Dieback:

Oak Wilt

• Trunk/Bark:

Beech Bark Disease	Sudden Oak Death

• Trees Affected
  Norway, sugar, silver, and red maple, horsechestnut, aspen (poplar), willow, elm, mulberry, and black locust and other hardwoods.
• Symptoms
  Very round rust colored holes (entry and exit wounds) about 3/8 to 1/2" in diameter along the branches or trunk of the tree.
• Importance
  Extremely destructive exotic pest that once established can kill hardwoods very rapidly.

• Prevention
  Early detection and prompt removal of dead or dying trees.

• Learn More
  Current Status, Research, and Management of the Asian Longhorned Beetle

Adult Asian longhorned beetle on a hardwood tree.

Round rust colored holes left by the Asian longhorned beetle.

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• Trees Affected
  All true furs, Abies spp., including balsam and fraser fir.

• Symptoms
  Infested crowns with abnormal drooping of current shoots and gouting of outer twigs. Crown becomes increasingly thin and dieback may occur. Stem attacks with conspicuous presence of white woolly masses often giving the lower bole a whitewashed appearance. Sapwood of infested wood swells causing gouting of twigs and increased heartwood formation.
• Importance
  A serious pest of forest, seed production, landscape, and Christmas trees. Stem infestations are usually more serious, causing greater levels of damage and mortality. Persistent crown infestation can kill a tree over a number of years.
• Prevention
  Early detection and prompt removal and destruction of dead or dying trees. Prescribed fire is often used to sanitize the site.

Balsam fir bark infected with Balsam Woolly Adelgid.

Gall-like formation on the twigs, due to Balsam Woolly Adelgid feeding.

Balsam fir needles infected with Balsam Woolly Adelgid.

• Trees Affected
  Eastern hemlock (Tsuga canadensis) & Carolina hemlock (T. caroliniana).
• Symptoms
  White cottony masses at the base of needles.
• Importance
  Destructive disease that can quickly kill hemlock.
• Prevention
  Early detection and treatments to avert establishment of populations.
• Learn More
  USDA Forest Service Hemlock Woolly Adelgid Site

Eastern Hemlock needles infected with Hemlock Woolly Adelgid.

Dieback on Eastern Hemlock due to Hemlock Woolly Adelgid.

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Foliage Dieback
A number of forest pests directly or indirectly affect the foliage on trees. Some pests eat or chew on the leaves or needles while other pests may injure parts of the tree which led to foliage dieback.

Oak Wilt

Trees Affected
White, and Red Oak

• Symptoms
  Bronzing or browning of green leaves from the tips/margins toward the leaf base.
• Importance
  Destructivedisease that can kill oaks very rapidly.
• Prevention
  Early detection and prompt removal of dead or dying trees. Avoid trimming, or cutting live oak trees during spring (May - June).

Oak wilt symptoms on red oak leaves.

Oak wilt defoliation.

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Trunk/Bark
The affects of some pests are most noticeable on the bark or trunk of the tree. Often times scales or wholes are left by the pest on or within the bark.

Beech Bark Disease

• Trees Affected
  American Beech
• Symptoms
  Small white scales are present on the bark of the tree.
• Importance
  Very destructive disease that can kill large stands of beech trees.
• Prevention
  Early detection and prompt removal of dead or dying trees. Avoid touching the infected tree or trees.

Scaling associated with beech bark disease.

White lichen often confused with beech bark disease.

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Sudden Oak Death

• Trees Affected
  (Quercus sp., Lithocarpus densiflorus); rhododentrons; huckleberry (Vaccinium ovatum); bay laurel (Umbellularia californica); and California buckeye (Aesculus californica); Big leaf maple (Acer macrophyllum); CA honeysuckle (Lonicera hispidula).
• Symptoms
  Cankers are formed on stems. Cankered trees may survive for one to several years, but once crown dieback begins, leaves often turn from green to pale yellow to brown within a few weeks.
• Importance
  Exotic lethal disease of oaks. Likely difficult to eradicate once established. Prevention
  Early detection and prompt treatment of site which includes prescribed fire.
• Learn More
  California Oak Mortality Task Force

Dark spots on bark with exuding brown to tar black
thick sap.

Bleeding or seeping from the main stem or trunk.

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