1. They are blind and follow a scent. Similar scent which we use in ball pens. So if you draw an 8 on a paper and place some termites on it they will do the figure 8 until the scent wears off.
2. The subterranean termites absolutely need moisture they cannot survive without it. For example if you put a termite in a cup and leave them there for a few days with out water the termite will simply dry out.
3. There are 3 classes of termites and they severely depend on each other. There are solders, worker and swarmers. Swarmers reproduce, solders protect and workers bring food and build tunnels.
So how do you know you have them. Well some obvious signs are severely damaged moist wood with holes and mud tubes. To be absolutely sure you should hire a licensed termite and pest inspector.
Now if you have termites does it mean you have to bomb your home with chemicals? The short answer is no there are other ways to mitigate the problem now. For example a short blog i have written earlier on Facebook on Bait mitigation. What this is a poisoned bait is buried for termites and since workers bring all the food back to the colony the entire colony will be affected.
Here is a picture of a piece of wood which has been destroyed by the wood destroying organisms. Note; the entire bottom of the wall of the house was in that condition.