Yeah, you don’t usually find a termite nest as the nest is usually in the ground and the only thing you see are mud tubes or the damages caused by them eating the wood in your home. If you see them eating your books then they are around.

Normally a pest control company would set traps or treat the ground so that the termites take poison back to their colony and kill the Queen.

The organization that I volunteer with, a friends of the library group, has a storage building that’s old and not in good repair. it holds a lot of donated books which we have sorted out and we open the building for book sales (and people pay whatever sum they want to donate so it’s really a bargain and get books back in the hands of people !).

We had an insect problem, so we called local pest control, they said it was termites, and did extermination. . But they also offered a service where they put baited traps around the outside perimeter of the building, and check them every three months or so for traces of termites. Then if they see any, they would know to come inside and look thoroughly. It cost extra but for us with thousands of books inside it was definitely worth it. I hope this might be helpful. Good luck!