Wood Boring Insects
Structural destroyers that attack trees, lumber, and timbers
About Wood Boring Insects
Wood boring insects are a broad category of beetles and other insects whose larvae tunnel through wood — living trees, structural lumber, log cabin walls, and decorative timbers. In the Northwoods, the most significant species include the emerald ash borer (devastating to ash trees), longhorned beetles, bark beetles, and various wood-boring beetles that attack structural and decorative wood. These insects can kill mature trees, compromise structural integrity, and cause extensive cosmetic damage to log homes and cabins.
How to Identify Them
- Emerald ash borer: metallic green beetle, 1/2 inch; D-shaped exit holes in ash trees; S-shaped galleries under bark
- Longhorned beetles: large beetles with very long antennae; round exit holes in hardwoods
- Bark beetles: tiny beetles that create distinctive gallery patterns under tree bark
- General signs: round or D-shaped exit holes in wood, sawdust-like frass, bark splitting or falling
- Woodpecker activity on trees is often a sign of wood boring insect larvae underneath
Why They're a Problem
Wood boring insects can kill mature trees and compromise the structural integrity of log homes, cabins, and timber-frame structures. The emerald ash borer has killed hundreds of millions of ash trees across North America and is well-established in Wisconsin. Infested trees become hazardous and must be removed. In structures, wood boring beetles can cause extensive damage to log walls, exposed beams, and decorative timbers before the infestation is detected.
Signs of Wood Boring Insect Activity
- D-shaped or round exit holes in tree bark or structural wood
- Sawdust-like frass around the base of trees or below infested wood
- Bark splitting, cracking, or falling from trees
- S-shaped or winding galleries visible under loose bark
- Canopy dieback or branch death in ash trees (emerald ash borer)
- Woodpecker damage on tree trunks — woodpeckers excavate to reach larvae
- Adult beetles found near windows or light sources in summer
How K2 Treats Wood Boring Insects
Treatment depends on the species and whether trees or structures are affected. K2 treats structural wood with residual insecticides and void injections. For trees, systemic insecticide treatments can protect high-value ash and other susceptible species from emerald ash borer. Severely infested trees typically require removal.
- 1Inspection to identify species, extent of infestation, and affected materials
- 2Structural wood treatment with residual insecticide to infested and adjacent surfaces
- 3Void and crack injection for inaccessible structural areas
- 4Tree assessment and systemic treatment recommendations for high-value trees
- 5Recommendations for removal of severely infested trees or wood
- 6Follow-up inspection to assess treatment effectiveness
Prevention Tips
- Have ash trees assessed and treated preventively before emerald ash borer arrives
- Inspect firewood carefully — never move firewood from infested areas
- Remove dead and dying trees promptly — they're breeding habitat for wood borers
- Seal and finish exposed wood surfaces on log homes and cabins
- Inspect structural timbers and log walls annually for exit holes and frass
- Maintain tree health — stressed trees are more susceptible to wood boring insects
Dealing with Wood Boring Insects?
Don't wait — call K2 for a free estimate and fast service anywhere in the Northwoods.
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