Understanding the Pest Risk
One of the most common concerns customers raise about reclaimed lumber is insects. The worry is understandable — wood that has been in a barn, warehouse, or old house for decades has had plenty of opportunity to encounter wood-boring insects. But the reality is more nuanced than the fear, and with proper processing and vigilance, pest issues in reclaimed wood are manageable and preventable.
The most important thing to understand is the difference between old, inactive insect damage (which is cosmetic and harmless) and active infestations (which require treatment). The vast majority of the insect holes and galleries you see in reclaimed wood are evidence of historical activity that ended long ago — the insects are gone, and the holes are simply part of the wood's character.
Common Wood-Boring Insects
Powder Post Beetles
Powder post beetles (family Lyctidae) are the most common wood-boring insects encountered in reclaimed hardwoods. They lay eggs in the pores of hardwoods like oak, ash, and walnut. The larvae bore through the wood, leaving small round exit holes (1/16 to 1/8 inch diameter) and a fine, flour-like frass (boring dust). The life cycle takes one to five years depending on species and conditions.
Active infestation is identified by fresh frass — fine powder that accumulates below exit holes or falls out when the wood is handled. If you see fresh frass, the infestation is active and must be treated before the wood is installed. Old, dark exit holes with no fresh powder indicate inactive, historical damage.
Old-House Borers
Old-house borers (Hylotrupes bajulus) target softwoods, particularly pine and fir. Despite the name, they actually prefer newer wood — they are attracted to the higher moisture and starch content of wood less than 10 years old. In reclaimed softwood lumber that has been seasoned for decades, old-house borers are rarely an active concern. Their oval exit holes (1/4 to 3/8 inch) are larger than powder post beetle holes.
Termites
Subterranean termites require ground contact and a moisture source to survive. They do not infest above-ground lumber that is kept dry. Properly stored and kiln-dried reclaimed lumber is not at risk for termite infestation. However, if reclaimed wood was stored on the ground in damp conditions before you acquired it, inspect it carefully for termite galleries — irregular, mud-lined tunnels running along the grain.
How Kiln Drying Eliminates Pests
The single most effective pest prevention measure for reclaimed lumber is kiln drying. At Norfolk Lumber, we kiln-dry our reclaimed inventory at temperatures of 130 to 160 degrees Fahrenheit for a minimum of 24 to 48 hours (depending on thickness). This heat treatment kills all life stages of wood-boring insects — eggs, larvae, pupae, and adults — without chemicals.
The USDA's ISPM 15 standard for heat treatment of wood requires a core temperature of 133 degrees Fahrenheit for 30 minutes to certify wood as pest-free. Our kiln schedules far exceed this minimum, ensuring thorough treatment even in the thickest timbers.
Can Insects Re-infest After Kiln Drying?
Theoretically, yes — if kiln-dried wood is stored in conditions where it is exposed to active beetle populations, re-infestation is possible. In practice, this is rare for properly stored material in a controlled environment. Once installed in a climate-controlled building, re-infestation risk is minimal because indoor humidity levels are too low to support most wood-boring beetle species.
What to Look For When Buying Reclaimed Wood
- Ask about kiln drying: Any reputable reclaimed lumber dealer should kiln-dry their inventory. If they do not, or if they cannot tell you their kiln schedule and temperatures, consider another supplier.
- Inspect for fresh frass: Handle boards and look for fine powder falling from holes. Tap the wood — active infestations sometimes produce a soft, punky sound in areas of heavy boring.
- Check for exit holes in context: Old exit holes that are dark, weathered, and sealed with patina are not a concern. Bright, fresh-looking holes with sharp edges and light-colored wood around them may indicate recent activity.
- Examine end grain: Larvae galleries are often most visible on end grain, where you can see the boring tunnels in cross-section.
Treatment Options If You Find Active Pests
If you discover active insects in reclaimed wood before installation:
- Re-kiln: The most effective option. Return the wood to a kiln for a full heat treatment cycle.
- Borate treatment: Borate-based wood preservatives (like Tim-Bor or Bora-Care) penetrate the wood and kill active insects while providing long-term protection against future infestation. Borates are low-toxicity to humans and pets.
- Freezing: For small pieces (furniture components, accent pieces), placing the wood in a chest freezer at 0 degrees Fahrenheit for 72 hours kills most wood-boring insects. This is not practical for large quantities.
Prevention After Installation
The best long-term pest prevention is moisture control. Keep indoor humidity between 30% and 50%, ensure good ventilation in crawl spaces and attics where reclaimed wood is used, and address any water leaks or condensation issues promptly. Dry wood is inhospitable to almost all wood-boring insects. Regular visual inspection — once or twice a year — gives you early warning of any developing issues.