Wood-destroying organisms (WDOs), also referred to as wood-destroying insects (WDIs) in some jurisdictions, are biological agents that attack and degrade timber. In the context of property inspections, WDOs typically include subterranean termites, drywood termites, wood borers (such as lyctid and anobiid beetles), and wood-decay fungi (commonly known as rot). Identifying WDO activity is a critical component of timber pest inspections conducted under applicable national standards such as NPMA-33 in the US or equivalent frameworks in other countries.
Types of Wood-Destroying Organisms
Subterranean termites are the most destructive WDOs worldwide. They live in underground colonies and build mud shelter tubes to travel between their nest and timber food sources. They can cause severe structural damage before any visible signs appear on the surface.
Drywood termites live entirely within the timber they consume and do not require contact with the ground. They are less common than subterranean species but can be found in coastal regions and tropical climates.
Wood borers are beetles whose larvae bore into timber as they develop. Lyctid borers attack the sapwood of hardwood timbers, while anobiid borers can affect both hardwood and softwood. Evidence typically appears as small flight holes and fine powdery frass.
Wood-decay fungi require elevated moisture levels to establish and grow. Brown rot fungi cause timber to become brittle and crumble, while white rot fungi degrade timber in a more fibrous pattern. Both types compromise the structural integrity of affected timber.
Inspection and Detection
Professional WDO inspections involve a visual examination of all accessible timber and a search for evidence of current or past activity. Inspectors use tools such as sounding devices, moisture meters, thermal imaging cameras, and microwave detection units to identify concealed activity. Properties with evidence of WDO activity may require further invasive investigation by a specialist.