Termites and other pests can cause expensive damage. Here's what to look for. The sawdust-like accumulations of frass indicate the presence of termites. An exterminator can spray or set traps to eliminate the infestation. A clean hole indicates an access hole for rodents. An exterminator can set traps for them, too.
For more on pests, consider:
DIY Pest Prevention (INFOGRAPHIC)
Pests, Be Gone! 10 Natural Ways to Make Your Home Critter-Free
The Complete Natural Guide to Apartment Pest Control and Prevention