Ceilings – timber boards damaged by borer

Cause

Untreated timber

Repair

  • if the borer infestation is active, treat infested timber with a residual insecticide by brushing on or spraying surfaces, ensuring that flight holes are drenched or preferably injected. Using a small spray nozzle to inject the liquid into the holes is effective, but wear eye protection as the spray may shoot out another hole towards you

  • if the infestation is extensive or fumigation is being considered, consult a specialist pest destruction firm that is a member of the Pest Management Association of New Zealand

  • borer holes are unlikely to result in major damage. The decision to replace infested timber is usually based on aesthetic reasons – whether the appearance of borer holes is acceptable or not

  • high moisture levels can be a factor in borer infestation. If moisture is a problem inside the house:

    • avoid using unflued gas heaters and avoid drying laundry inside – these add a lot of moisture to the air

    • opening windows for at least 10 minutes every day can make a difference to indoor air quality

    • increase the amount of ventilation provided. In particular, add a rangehood over the kitchen stove and an exhaust vent near the shower in the bathroom, both vented to remove steam to outside the house. An alternative to reduce bathroom steam is to fit a proprietary plastic dome over the shower to keep the steam inside.

Cause

Damp environment

Repair

  • if there are high internal moisture levels:

    • avoid using unflued gas heaters and avoid drying laundry inside – these add a lot of moisture to the air

    • opening windows for at least 10 minutes every day can make a difference to indoor air quality

    • increase the amount of ventilation provided. In particular, add a rangehood over the kitchen stove and an exhaust vent near the shower in the bathroom, both vented to remove steam to outside the house. An alternative to reduce bathroom steam is to fit a proprietary plastic dome over the shower to keep the steam inside

  • if the borer infestation is active, treat infested timber with a residual insecticide by brushing on or spraying surfaces, ensuring that flight holes are drenched or preferably injected. Using a small spray nozzle to inject the liquid into the holes is effective, but wear eye protection as the spray may shoot out another hole towards you

  • if the infestation is extensive or fumigation is being considered, consult a specialist pest destruction firm that is a member of the Pest Management Association of New Zealand

  • borer holes are unlikely to result in major damage. The decision to replace infested timber is usually based on aesthetic reasons – whether the appearance of borer holes is acceptable or not.