Termite activity on a foundation(C) Daniel Friedman Termite Mud Tubes
How to recognize termite damage, termite mud tubes & what they mean when found in or on buildings or other structures

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Termite mud tubes & passages:

What is a termite mud tube and how are they recognized? What do termite mud tubes tell us about the age, location, and extent of termite activity or wood destroying termite damage in or on a building or on other wood structures. Where are termite mud tubes found? What happens if we disturb a termite mud tube? Are outdoor termite mud tubes a concern?

This article series provides a case study of a termite inspection that found insect & rot damage:photographs, inspection advice & visual clues that led to discovery of severe hidden structural damage to a building.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Termite Mud Tubes - Important Indicators of Termite Damage

Termite Damage Mud Tubes Photographs Suggest Where to Look

Our termite damage photograph at below left illustrates that carpenter ant activity (frass or loose "sawdust) may be found in the same location as termite activity (the mud tubes).

Signs of risk of termite attack © Daniel Friedman at Signs of risk of termite attack © Daniel Friedman at

Our second termite mud tube photo (above right) is more clear and shows branching termite mud tubes running along the surface of a floor joist.

Watch out: termites prefer to tunnel inside of wood and can cause extensive damage without appearing readily on the wood surface. Mud tubes are typically built to enable movement across a less hospitable surface such as masonry walls or wood that was just not so nice to penetrate. Termites had traveled extensively in the ceiling joist shown in our photo at below-left. The sill plates located on the floor in this same room were also infested (photo below right).

Hanging Termite Mud Tubes - Termite Stalactites

Reader Question: We noticed some hard stalagmite looking things (pictures attached) in our basement and we were wondering if these are from termites? - G.M. 8/3/2014

Hanging termite mud tubes or termite stalactites (C) InspectApedia GM Hanging termite mud tubes or termite stalactites (C) InspectApedia GM

[Click to enlarge any image]

Reply: I'm sorry to say yes, that looks like significant and active termite activity. The hanging mud tubes are the critters' exploration for another wood contact avenue besides the beam that they already infest.

Because those hanging mud tubes are quite fragile I infer from your photographs that either they are located in an area where no one has passed for some time or the termite activity is voracious.

Steps to Address Hanging Termite Mud Tubes

1. Call a pest control company to inspect for the location and extent of activity and to treat the termite activity.


2. Determine the extent of structural damage and thus what repairs are needed.

See the FEAR-O-METER a promotion theory to convert risk of hidden defects & hazards into action thresholds, for a discussion of how an accumulation of inspection evidence leads to a rational decision to perform invasive or destructive inspection measures such as removing siding or cutting into walls or floors where hidden termite damage may be most likely.

3. Determine building or site factors that increase the risk of termite activity and correct those, such as wood-soil contact, building leaks, splash-up of roof drainage against building walls, wet basements.



Termite Mud Tubes on Foundation Walls

Below our termite mud tube photos illustrate how extensive branching mud tubes may be found on building foundation walls headed for wood framing members and even along metal pipes. At below left it appears that termites entered through a crack in the foundation wall, then built mud tubes upwards looking for a more hospitable wood material.

Termite activity on a foundation(C) Daniel Friedman Termite activity on a foundation(C) Daniel Friedman

Termite Mud Tubes at Wood Framing Intersections & in Wood Beam Checking Splits

Below our termite mud tube photos illustrate the importance of a careful, expert termite inspection. The mud tubes at below left are close to and tightly located against the junction of subfloor and rim joist, and the butt end of a floor joist and rim joist and are not as easy to spot as our earlier termite photographs.

And at below right we demonstrate that termites might run along the interior of an old wooden beam; we found these termite tunnels by probing inside the large open checking or splits that would normally be considered not a structural concern, but adding termite damage can change that evaluation.

See SPLITS & CRACKS in STRUCTURAL WOOD BEAMS for more about log and beam checking or splitting.

Termite activity on a foundation(C) Daniel Friedman Termite activity on a foundation(C) Daniel Friedman

Below we illustrate additional termite mud tubes running horizontally inside the checking of an older wood floor beam in the same building that sported the termite stalactites illustrated above.

Termite mud tubes horontally located in checking splits in a wood beam (C) InspectAPedia - GM

Photo Guide to Termites & Termite Mud Tubes Outdoors

Arizona termites exposed in sunlight (C) D Friedman M Gieseke

Termite mud tubes may appear on the outside (photo at left) or inside of building walls or other structural components (photo at left) or they may appear on the ground itself (below left).

These Arizona termite mud tube photos just below were contributed by our Arizona correspondent (and daughter) Mara Gieseke, Tucson AZ who reports:

So what do you think of these Arizona Desert Termites ... I went out back today to try and get some pictures for you.

I got one photo of the termite mud tubes that are on a masonry retaining wall that is quite a distance from our house.

Then I swiped my shoe over the mud trails (below left) that I saw in the dirt, but there were no termites in any of them.

Where did they go?

The other time I kicked open a termite mud tube there were at least 50 Arizona termites squirming in the mud (below right).

Arizona termites exposed in sunlight (C) D Friedman M Gieseke Arizona termites exposed in sunlight (C) D Friedman M Gieseke

[Mara Gieseke's termite photo (above right) shows Arizona termites squirming in the sunlight just after she disturbed their ground-surface mud tube. We have enlarged this photo to make the termites easier to see, but notice how difficult it is to spot them against the sandy soil found in the Tucson area. How big are termites in actual life-size?

If you could get these termites to line up in single file and march across a U.S. dime, you'd see that if they marched along the diameter of the dime there would be at least five of them. Typical termites are 5.5 mm in length but vary in size from about 1/8" long to as much as 3/8" for the big boys.

Queen termites are bigger, over 3/4" in length excluding a pregnant queen's abdomen that, if included can make her total size 2" or even more. There are about 2800 termite species that have been identified, grouped in seven families (including the largest family, Termitidae), and it is probable that there are other species not yet classified.]

The retaining wall is 20 feet from the house, and we found tubes growing vertically in the grass too. I also got a picture of a section of dirt that has lots of those mud trails.

We've have never had termite activity inside the house. The first year that we lived here we had to have the pest control people out here several times to treat the expansion joint where the back patio meets the house.

What Happens if We Disturb or Break Open Termite Mud Tubes

Disturbing a termite mud tube is shown just below. They won't bite you, but some genera/species of termites will indeed bite a wood structure or its wood siding or trim.

If you disturb a mud tube and termites fall out you know for sure you've found an active colony. Unfortunately the converse is not necessarily true. If you disturb a mud tube and don't see any termites, you'll need more information and probably a more expert inspection before you know if there is ongoing termite activity or not.

Signs of risk of termite attack © Daniel Friedman at Signs of risk of termite attack © Daniel Friedman at


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