I think this might be referring to the mud tubes they build.

HTH


Sheila


Mud tubes on walls located outside or inside the structure, which often disappear into cracks of masonry, in and around doors and window frames or along siding. Termites construct mud tubes to protect themselves as they bridge from soil to wood. The tubes can be 1/4 inch in diameter and can extend many feet across solid surfaces.

http://www.dowagro.com/sentricon/us/property/maintaining/rec...

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Note added at 34 minutos (2006-08-04 18:24:49 GMT)
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Termite tubes are another danger signal to watch for. Because they prefer dark, moist conditions, termites make these earth-colored tubes primarily as protected runways from the earth to the wood they feed on. They also may serve as swarming exits for winged termites.

"Look for these tubes on cellar walls, wooden posts, exterior masonry and trim around doors and windows," Jacobs says.

http://aginfo.psu.edu/PSP/03psp/pr/03119_pr.html

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Note added at 36 minutos (2006-08-04 18:27:02 GMT)
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Les termites sont lucifuges et redoutent toute exposition à l'air. Ainsi, les galeries faites par les termites sont de deux types :

• soit creusées dans le sol ou les matériaux tendres tels que le bois, les matières plastiques, le plâtre ;

• soit construites avec un mélange de terre, de particules de bois, d'excrément et de salive à la surface de matériaux trop durs pour pouvoir être forés, comme le béton, le ciment et la pierre. Elles forment alors un réseau de petits cordons ou cordonnets courant sur les murs.


http://www.senat.fr/rap/l96-184/l96-1848.html



http://www.anti-termite.com/htfr/0019.htm