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Pest Control/strange material on drywall with some tubing


Inside of wall near studs
Inside of wall near st  
Back of Drywall
Back of Drywall  
QUESTION: Hi Mr. DeAngelis.  About a week ago, my wife and I discovered that we had a leak in our aquarium in the living room that had dripped down through the drywall and into/under the laminate flooring.  After removing the damaged section of flooring and drying out the subfloor, I moved on the drywall.  After removing a section where the drip from the tank was going down the wall, I noticed some black stuff on the plastic behind the wall.  I thought it was mold and sprayed it/cleaned it up.  However, I noticed that on a few of the pieces of laminate, there were weird paths through the foam underlayment attached to the wood.  None of the wood was damaged however.  After investigating more today, I pulled more drywall off to notice that the back of about a 32 in section of drywall between three studs was also covered with this weird, black and gray sandy type of material.  I saw similar paths on the back of the drywall as I did on the flooring, with some tubes.  What was weird is that none of the drywall itself was damaged - it was just the thin paper covering of the drywal.  

In doing more investigation, I noticed that there was some more of this stuff along the studs inside the wall where the outside wall board meets the stud.  It goes all the way up to the ceiling.  I don't know if it extends to the second floor.  

I have seen NO bugs which is weird and no damage to any wood/studs, at least that I can see.  I have dealt with termites before and know the damage they can do to studs and joists.  

I have attached a few pictures.  Perhaps this is just some form of mold because this was a slow leak rather than just a massive flood but the tubing had me curious/a little worried.  If you have any ideas or suggestions for me, I would appreciate it greatly.  Thank you very much and have a great holiday.


I don't think this is mold. The texture and pattern looks more like termite shelter tubes (see for a drawing). If this is right then the next question is whether or not the colony is active. If you don't find termites inside the tubes then these may be inactive (old) shelter tubes. The tubes may not be related to the water leak. Check around the foundation for an active shelter tube network on this side of the house. Has the house been treated for termites recently? Since any termite infestation will be treated at the soil level there's no need to treat the walls while they are open for construction. At some point you may also want to deploy termite bait stations around the house to detect any activity (see for general info). Post a follow up if you have questions.

Jack DeAngelis

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QUESTION: Thank you Mr. DeAngelis. I have looked all over the internet for different pictures of mold and haven't seen anything that looks like this so I agree there.  However, would the fact that there were no bugs whatsoever be an issue?  I guess if it was an inactive colony the lack of any termites would make sense.  It just seemed to be such a big coincidence to have this material only in the area where the leak was.  Should I continue up the drywall (including the second floor) to see if there is a colony somewhere or (like my father-in-law said) just put the drywall back on and not worry about it?

The fact that there is no damage to any of the wood is what puzzles me too.  If it was an older, inactive colony, wouldn't there have been some damage to the wood studs in the area?  Only the thin paper on the drywall showed damage. I haven't seen any thing else, including the base plate of the wall and the subfloor.   There is no noticeable change below the floor or wall in the garage (basement) as well.

The material itself almost look like tiny little pebbles which is also weird and puzzling.  Almost like little rocks or grains of sand.

We did have termites in a small area on the other side of my house a year or so ago but the inspector at the time did not see any evidence of termites anywhere else in the house.  I treated that side with termidor and also used some termite-prufe borate spray on the wood along with a termite foam into the areas affected from the inside.  I have not checked this side of the house but it is winter here in Pittsburgh so I don't think I would see anything anyway due to the ground being frozen.

Thanks for your help. Any advice to some of these points is appreciated.  This really has me puzzled.

ANSWER: In your area termites are not necessarily associated with moisture so the leak may have nothing to do with these tubes. I think you can safely replace the drywall BUT you should do a thorough inspection for termite activity (see This inspection (and treatment) is done at the ground level (see for control info). The actual damage may be higher, or lower, from where you uncovered these tubes. Shelter tubes are made from soil particles so the gritty nature is what you'd expect.

Jack DeAngelis

---------- FOLLOW-UP ----------

QUESTION: Thanks again for your response.  So not having any damage on the wood studs or baseplate or subfloor is not a big deal?  That just didn't make any sense to me, especially if it was an inactive colony that had been there before.

Last question - I can treat that side of the house with the termidor trench even if it's just a precaution but should I wait until spring or at least until it gets warmer?  Are termites dormant in the winter?  

Thanks again for all of your help and have a very merry holiday season.

Think of shelter tubes as tunnels that the termites use to move from point A to point B. Point A is the main colony in the soil, point B is the end of the tunnel system where feeding (and damage) is occurring. If these are shelter tubes you may be looking a section between A and B where they did not feed for some reason.

Termites will be active whenever the temperature of the soil and their shelter tubes is high enough (for most insects this is above about 55 deg. C).

You may want to wait until spring to treat but do your inspections this winter.

Merry Christmas,

Jack DeAngelis  

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Jack DeAngelis


I can answer questions about the control of pest insects, spiders, mites and related arthropods. These household pests include termites, carpenter ants, powderpost beetles, nuisance ants, bed bugs, cockroaches, fleas, wasps, and many others. I can also answer questions about using pesticides and other pest control tools such as baits and traps.


I am a retired university extension entomologist. I've taught and conducted research in urban and agricultural entomology. I've published over 70 extension publications, 20 research publications and several books about insects.

Ph.D. in Entomology

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