We often get calls when people find some dust, debris or any fine material that appears out of places it probably shouldn't. Good news is, it's not always termites, but it's bad news when it is. How can you identify what it is?
Termites build mud shelter tubes to keep them nice and cozy and moist, they can't be exposed as they will dehydrate and die. So, keeping this in mind, you need to remember that you're looking for nice moist, tightly packed mud. If the termite activity isn't new, the mud may be quite dry and cracked, but it's normally quite dense and difficult to break off. Termites are great engineers, and they will build solid mud tubes that protect them from the outside world.
If you see any debris or something that isn't where it should be, give it a rub with your finger, if it's hard and doesn't break away easily then it could likely be termite mud!
Here are some pictorial examples of what to look for:
Here is a deceptive example: