Wood-Boring Insects in Atlanta Trees: Identification & Management

What Are Borers?

"Borers" is a general term for insect larvae and adults that tunnel into the bark, sapwood, or heartwood of trees, disrupting the tree's ability to move water and nutrients. In the Atlanta area, the most common offenders are granulate (Asian) ambrosia beetles, emerald ash borer, flatheaded and longhorned beetles, and clearwing moth borers.

How to Recognize It

• Tiny round or D-shaped holes in the trunk or main branches (D-shaped holes are typical of emerald ash borer and other flatheaded borers).
• Toothpick-like strands of sawdust pushed out of small holes, a classic sign of ambrosia beetles.
• Sawdust-like frass or sap weeping from holes on the trunk.
• Thinning canopy, dieback starting at the top of the tree, or sudden wilting of new spring foliage.
• Cracked, splitting, or sloughing bark, sometimes with S-shaped tunnels visible underneath.
• Increased woodpecker activity on the trunk and large limbs.

Many borer species, including the granulate ambrosia beetle, begin their main flight in late winter and early spring (roughly February through April in Georgia) as trees leaf out. Symptoms from an earlier stress event such as drought, flooding, or storm damage often do not appear until the following spring or summer.

Why It Matters for Atlanta Trees

Borers are often fatal once they are established inside the wood, because they damage the vascular tissue that moves water and nutrients. Emerald ash borer kills nearly all untreated ash trees it infests, and as few as a handful of ambrosia beetle attacks can kill young or stressed trees. Because dying trees become brittle and prone to dropping limbs or falling entirely, borer-infested trees near homes, driveways, or walkways can become a real safety hazard, which is why early identification matters.

In Atlanta yards, the trees most commonly affected include ash (especially vulnerable to emerald ash borer), crape myrtle, dogwood, redbud, Japanese maple and other maples, oak, cherry and other ornamental fruit trees, Bradford and other ornamental pears, pines (susceptible to bark beetles such as southern pine beetle and Ips beetles), and hickory and elm.

General Prevention

• Keep trees healthy and unstressed. Water deeply during Atlanta's summer droughts and avoid both underwatering and waterlogged soil, since borers preferentially attack stressed trees.
• Protect the trunk and root flare from mechanical damage by mowers, string trimmers, and construction equipment, since open wounds attract egg-laying adult borers.
• Plant trees at the correct depth with a 2 to 4 inch ring of mulch (not piled against the trunk) to reduce stress and protect roots.
• Promptly remove and properly dispose of dead or heavily infested wood so it does not become a breeding reservoir for the next generation of beetles.

What NOT to Do

• Do not self-diagnose. Many tree problems look alike, and treating the wrong one wastes time and can harm the tree.
• Do not apply fungicides, insecticides, or other chemicals without an arborist's specific recommendation. Wrong product or wrong timing makes things worse.
• Do not plug, paint over, or seal borer holes. It does not stop the insects already inside, and it can hide the spread of an active infestation from anyone trying to assess the tree.

Related Services

For most diagnosis and treatment questions, the right starting point is one of our services:

• ISA-Certified Arborist Services for diagnosis, consultation, and second opinions.
• Plant Health Care (PHC) for ongoing tree health management.
• TRAQ Tree Risk Assessment for when the tree may be a safety hazard.

Sources

This page summarizes general information from: University of Georgia CAES (UGA Extension), Alabama Cooperative Extension System, University of Georgia (UGA Today), and Georgia Forestry Commission.