Another obvious indication that will alert an exterminator to a termite problem is the presence of mud tubes. You may find them along your foundation, near your pipes, in your crawlspace, in your attic or around other access points to your home. Also called shelter tubes, mud tubes are like covered highways termites use to traverse open, exposed spaces like concrete footers. They can't go through these obstacles, so they build highways over or around them.
Mud tubes are made of soil, wood cellulose and other particulate matter. Termites dehydrate quickly, so they need the protection of an enclosed environment to maintain the humidity levels they need to survive. The tubes also protect them from predators. Mud tubes are about the thickness of a drinking straw or pencil and look like encrusted, dried dirt. They can be squiggly or straight. If you see a mud tube and don't know if it's from an old termite infestation or not, remove a small section, leaving the two ends of the tube undisturbed. If the breach seals back up in a few days, termites are currently active around your property.