Wood Borers in Plywood and Blockboard: Why It Happens

Many people assume engineered wood such as plywood and blockboard is borer-proof, because it is processed and glued. It is not. Borers can attack the wood inside these boards, particularly when untreated and when made from vulnerable timbers, and modular furniture is made largely of them.

This guide explains why it happens and how to reduce the risk.

The short answer

Wood borers attack plywood and blockboard because the veneers and core strips are made from timber, often fast-growing or sapwood-rich species that contain starch and are vulnerable, and because untreated boards, exposed edges and drilled holes give borers easy access. Damage may be hidden inside the board, with only tiny exit holes and fine powder showing. Reduce risk by choosing treated, borer-resistant boards with documentation, sealing cut edges and holes, controlling humidity and avoiding damp contact. Existing infestations need professional treatment, and badly damaged panels may need replacement.

Why engineered wood is vulnerable

• Timber content: Plywood veneers and blockboard core strips come from timber, sometimes of species that are attractive to borers.
• Starch and sugars: Some timbers contain more starch, which beetle larvae feed on.
• Exposed edges: Cut edges and holes expose the interior.
• Untreated boards: Not all boards are preservative-treated.
• Moisture: Damp boards weaken and attract pests.

Plywood versus blockboard

1. Plywood: Layers of veneer glued together. Borers can tunnel along layers, and the glue line may not stop them.
2. Blockboard: A core of wooden strips between veneers. The core can be attacked, and hidden damage may be extensive.

Signs in furniture

• Tiny round exit holes on surfaces and edges.
• Fine powder under wardrobes, beds and cabinets.
• Bubbling or lifting laminate and veneer.
• Hollow or soft panels.
• Sagging shelves.

How to reduce risk

1. Choose treated boards: Ask for borer-resistant or preservative-treated boards, and for documents.
2. Seal edges and holes: Treat and seal all cut edges, drilled holes and joints during installation.
3. Control moisture: Keep humidity down and fix leaks and damp walls.
4. Raise units off the floor and away from damp walls.
5. Inspect regularly: Check the back, base and edges.
6. Check before buying: Inspect second-hand modular furniture.

If infestation is found

• Photograph signs and isolate the item.
• Call a professional for identification, since termites also attack plywood.
• Treatment usually involves injection and surface treatment, and may include fumigation for severe cases.
• Replace panels that are badly damaged.

Borers or termites?

Termites leave mud tubes and soil, borers leave powder and round holes. Both can occur.

When to call a professional

If you see holes or powder in plywood furniture, call a professional to prevent spread through the home.

Frequently asked questions

Is borer-proof plywood really borer-proof?

Treatments reduce risk but are not a guarantee.

Can laminate stop borers?

It covers the surface but not edges and the back.

Can damaged plywood be repaired?

Minor damage can be filled. Severe damage needs replacement.

Does MDF get borers?

It is less commonly attacked, but can be damaged by termites and moisture.

This guide is part of IPest's complete resource on wood borer control. For identification help, prevention and treatment options, see our full wood borer treatment guide for Bangalore.