Termites are called "silent destroyers" for good reason. They can spend years consuming the structural wood in your home before you see any obvious signs of damage. By the time most homeowners notice something is wrong, thousands of dollars in repairs may already be inevitable.
The good news: termites do leave clues. You just need to know where to look.
1. Mud tubes on your foundation or walls
Subterranean termites — the most common species in Illinois — build pencil-width mud tubes to travel between the soil and their food source (the wood in your home). These tubes are typically found along your foundation, in crawl spaces, and along basement walls. If you spot a mud tube, don't just knock it down and assume the problem is solved; the colony is almost certainly still active.
2. Wood that sounds hollow when tapped
Termites eat wood from the inside out, leaving only a thin veneer of paint or wood surface. Tap along baseboards, door frames, and window sills with a screwdriver handle. A hollow thud — instead of the solid knock you'd expect — can indicate termite damage inside. You may also notice wood that appears to bubble or ripple slightly, even when there's no moisture source.
3. Discarded wings near windows and doors
In spring, reproductive termites (called swarmers) leave the colony to establish new ones. After they land and pair up, they shed their wings — which look like tiny fish scales, about the size of a sesame seed. Finding a pile of wings near a window sill or doorway, especially in spring, is one of the clearest warning signs that a colony is nearby.
4. Doors and windows that suddenly stick
Termite damage in door and window frames can cause wood to warp as it is eaten away, making doors and windows difficult to open and close. While sticking doors can also be caused by seasonal humidity changes, if you notice this symptom alongside any of the others on this list, it's worth having a professional take a look.
5. Frass (termite droppings)
Drywood termites, which are less common in Illinois but not unheard of, push their droppings — called frass — out of their tunnels through small kick-out holes. Frass looks like tiny, six-sided pellets and often accumulates in small piles that can resemble fine sawdust or coffee grounds near baseboards and window sills.
If you find any of these signs, resist the urge to disturb the area. A professional inspection can determine the species, the extent of the damage, and the best treatment approach.
What to do if you spot these signs
Don't panic, but don't wait either. Call a licensed pest control professional for an inspection. Early detection dramatically reduces both the treatment cost and the structural damage. The inspector will identify the species, locate the colony, and recommend a treatment plan — typically baiting systems or liquid treatments for subterranean termites.
Prevention is equally important. Eliminate wood-to-soil contact around your home, fix moisture issues in crawl spaces, and keep firewood stored away from your foundation. Annual inspections are the most reliable way to catch problems early.
