Mud tubes on the foundationthe termite highway up your slab

Mud tubes are tunnels of soil, saliva and droppings that subterranean termites build to move between soil and wood. Finding them on your foundation means termites have been there. Whether they are active now can be checked by breaking a small section and seeing if it is repaired. Either way, a professional inspection is the next step.

Subterranean termites have soft bodies that dry out quickly. They need humid conditions, so they travel underground or inside wood. When they must cross concrete, brick or other surfaces, they build tubes to stay protected. On a Houston slab house, tubes often run up the exposed slab edge to the sill plate or siding. On a pier-and-beam house, they run up piers to the beams.

Break a small section of tube, a few inches long, and look inside. If you see small pale insects, termites are active. If the tube is empty, check back after a few days. Rebuilt tubes indicate activity. Old, dry tubes that crumble and are never rebuilt may be from past activity, possibly before a treatment. Note the spot and tell the professional.

Look along the slab edge, especially behind shrubs and under mulch, at expansion joints in the garage, around plumbing and air conditioning lines entering the house, on piers and beams in crawlspaces, and on brick ledges. Tubes can also appear inside on walls, in closets or behind baseboards.

If termites are active, a professional will usually recommend a liquid barrier treatment, bait stations or both. Tubes are left in place until treatment is done, then removed so any new activity is easy to spot. Fixing moisture sources near the tubes helps keep termites away.

In brick veneer homes, termites can build tubes in the air gap between brick and framing. From outside you may see only a small tube at a weep hole or none at all. Inside, damage may appear at the base of exterior walls. If soil or mulch covers the brick ledge, pull it back so the ledge and weep holes are visible.

Garage slabs often meet the house slab at an expansion joint, a strip of fiber or foam between the two pours. Termites can come up through that joint and build tubes on the garage wall. Stored boxes, shelving and tools hide them. Clearing the base of garage walls once in a while makes tubes easy to spot.

Under raised houses, termites build tubes up brick or concrete piers to reach beams. Wooden piers may be eaten from inside without visible tubes. Crawlspace tubes can be long and branching. Checking piers with a flashlight from the crawlspace opening, if you cannot safely go in, may still reveal tubes on nearby piers.

After treatment, termites inside tubes may die off and tubes may be abandoned. Professionals often remove tubes after treatment so any new ones are easy to see. If new tubes appear, call the professional to check the treated zone.

The single most useful habit is keeping a few inches of slab edge or brick ledge visible all around the house. That means no soil, mulch or pavers piled above it. A visible edge makes new tubes obvious during a quick walk around the house.

Inside, tubes can appear running up drywall, along baseboards, out of cracks in tile floors or hanging from ceilings. Interior tubes usually mean termites are well established. Leave them in place for the professional, take photos and avoid spraying them, which can scatter termites into other areas.

Mud dauber wasp nests are tube-like but usually on eaves and walls well above ground, in clusters of short tubes. Dried mud from splashing rain can streak foundations. Tree roots and vines leave lines too. Termite tubes are flattened, about pencil width, gritty and connect soil to wood. Breaking one shows a hollow channel inside.

Tubes often appear near hose bibs, air conditioner drains, downspouts and plumbing penetrations, because termites need moisture and these spots stay damp. Fixing leaks and redirecting water reduces the appeal of those spots.

Take a wide photo showing where on the house the tube is, and a close photo with a coin or tape measure for scale. Note the date. If you break a section, photograph it again a few days later.

Colonies span property lines, so neighbors finding tubes is a reason to check your own foundation closely.

Indoors, termites can build short tubes up from cracks in a slab, under carpet or at the edge of tile. Pulling back carpet at a corner sometimes reveals them. Such tubes mean termites are coming straight up through the slab, which the professional will treat at that spot.

Spraying store insecticide into a tube kills a few termites but leaves the colony untouched and can push foragers to build new tubes somewhere harder to find. Leave treatment to the professional so the colony is targeted.

Narrow exploratory tubes suggest termites are searching; wide, well-used tubes suggest an established route to wood.