Well, if you see dirt tubes on your walls, or hear a dull munching sound, you might have termites. …unless there is someone eating breakfast in the next room.
Termites need to maintain a high level of moisture in their atmosphere in order to survive, and so they build mud-wall tunnels which keep the moisture in, even when they are eating very dry wall studs and floor joists. They are blind and somewhat erratic, so it is usual for them to accidently tunnel out into dry air, retreat, and patch the hole with mud. So mud spots are also an indicator of termites.
It usually pays to have a professional inspect the home to see if termites are evident. After a while, professionals will notice minor indications of termites which amateurs tend to miss.
Generally the mud tubes come up from below a slab or out of dirt. In a garage or in a wall, any crack is big enough.
This tube was built up the middle of hollow block, came out the light switch box and up into the door frame.
If you break the tube open and they build it back, it’s active.
Termites swarm up through cracks in a garage floor.
Bailing out of drying wood in a van, and eating and building mud tubes through spray foam insulation.
This crawl space had a steam leak for a year. Termites were everywhere and the moisture level after a month of drying out was still over 30%.
Look closely into the rings and see termites working on the soft wood.
This was an inaccessible vault under a hallway. Inspection was done by reaching over the sill plate with a camera and taking photos at different angles to see what showed up. Two swarm castles about to launch were found. The house was treated for termites seven months earlier, but the treating company failed to find the void, and did not treat it. Thoroughness counts.