Despite your worst nightmares, you won't hear a distinct munching sound. And these guys don't hide in plain sight, so you need to scout out places where wood framing is exposed, like crawl spaces. Inspect them for raised, branchlike tubes that, when broken open, reveal cream-colored or yellowish insects. Also, check where siding meets the foundation for salt-size droppings or tiny clumps of dirt next to pinholes. If you spot even one, you need a licensed and bonded exterminator to squash those tunneling bugs.
Common Bug Killers and Their Advantages and Disadvantages Bugs at Our Billerica Project