Signs of Termite Infestation in Your Home

Why Early Detection Matters

Termites cause more structural damage annually than fire, flood, and wind combined in the United States. In the North Bay, where older housing stock is prevalent and the climate supports year-round termite activity in both drywood and subterranean species, detecting an infestation early is the most powerful cost-saving measure available to homeowners.

The problem is that termites are cryptic insects that spend most of their lives inside wood or underground. The most common sign of an advanced infestation is no visible sign at all — a termite inspector with the right tools, probing the right locations, is often the only way to find activity before visible damage appears. This guide covers the signs that are visible to homeowners and explains how inspectors find what homeowners cannot.

Sign 1 — Termite Frass (Drywood Termite Pellets)

Drywood termite frass is the most diagnostically reliable sign of active drywood termite infestation. Frass consists of fecal pellets that termites push out of kick-out holes in infested wood — small, round holes barely visible to the naked eye. The pellets are six-sided, roughly 1mm long, and vary in color from tan to reddish-brown to dark brown depending on the wood species being consumed. They accumulate in piles below kick-out holes and are commonly found on windowsills, hardwood floors, in attic insulation, inside drawers below wooden furniture, and at the base of exterior trim.

• Fresh frass is soft and brightly colored
• Older frass hardens and darkens over time
• A single kick-out hole can produce thousands of pellets
• Pellets on painted surfaces leave round entry holes about the size of a pencil tip
• Drywood frass does NOT look like sawdust — it is granular and uniform in size

Sign 2 — Mud Tubes (Subterranean Termites)

Subterranean termites build shelter tubes — narrow tunnels constructed from soil, wood particles, and feces — to travel between their underground colony and the wood they are feeding on. These tubes protect termites from desiccation and predators. In North Bay homes, mud tubes are most commonly found on concrete foundation walls, across the surface of crawl space piers, along the exterior of the foundation, inside utility chases, and on the faces of stucco or brick siding at grade level.

• Active tubes contain live termites when broken open
• Inactive tubes are hollow and crumble easily
• Even inactive tubes confirm past subterranean termite activity
• Tubes range from pencil-width to over an inch in diameter in heavy infestations
• Finding tubes indoors (in finished wall cavities, behind drywall) indicates significant colony establishment

Sign 3 — Termite Swarmers and Discarded Wings

Winged termites (alates) are reproductives produced by a mature colony to establish new colonies. When swarming conditions are right — typically after rain for subterranean species in late winter/spring, or on warm evenings in late summer/fall for drywood species — swarmers emerge in large numbers, often appearing suddenly in large groups near windows and light sources.

• Subterranean termite swarmers: dark brown-black body, white equal-length wings, emerge January–April
• Drywood termite swarmers: reddish-brown body, equal-length wings, emerge August–October after warm days
• Swarmers are poor fliers and quickly shed their wings after a short flight
• Finding piles of discarded wings near windowsills or door frames indicates swarming has occurred
• Seeing swarmers inside a structure almost always means the colony is already established inside that structure

Sign 4 — Hollow or Damaged Wood

Termites consume wood from the inside, leaving a thin outer shell that conceals the damage until it becomes severe. Tapping suspected wood with a screwdriver handle produces a hollow, papery sound rather than the solid sound of undamaged wood. In advanced infestations, light pressure from a finger or probe causes the surface to collapse inward, revealing galleries below.

• Check wood with a probe in areas with high moisture or past termite history
• Baseboards, window frames, floor joists, and exposed beams are common hollow-wood locations
• Blistering or uneven paint on wood surfaces can indicate subterranean termite tunneling just beneath
• Sagging floors or ceilings can indicate extensive structural damage from long-established colonies

Sign 5 — Tight Doors and Windows

Subterranean termites produce moisture as they digest cellulose — this moisture can cause wooden door frames and window frames to swell, making doors and windows noticeably harder to open or close. This symptom is frequently attributed to seasonal humidity changes and overlooked as a termite indicator.

• Most significant in spring when subterranean termites are most active
• Occurs in frames adjacent to infested structural wood
• Combined with other signs, warrants immediate professional inspection

What Inspectors Find That Homeowners Cannot

Professional termite inspectors use specialized tools to detect termite activity that is completely invisible without them: moisture meters identify elevated moisture in wall assemblies and subfloor areas that indicate active subterranean termite colonies; probing tools assess wood density; borescopes allow inspection inside wall cavities without opening the wall; and acoustic emission detection can identify the vibrations of termite feeding activity in structural members.

This is why annual professional inspection remains the most important protective measure for any North Bay property — regardless of how careful a homeowner is in watching for visible signs.

Frequently Asked Questions