Finding a bug in your house starts with knowing where to look and what evidence to search for. Whether you’re tracking down an insect pest or sweeping for a hidden surveillance device, the approach is the same: systematic inspection of the places these unwanted visitors hide. Both types of “bugs” leave telltale signs if you know how to read them.
Narrow Down What You’re Dealing With
Before you start pulling furniture away from walls, take stock of what tipped you off. A single live insect sighting, unexplained bites on your skin, or tiny droppings on a shelf each point toward a pest problem. Strange sounds from your phone, a device you don’t recognize on your Wi-Fi network, or an object in your home that wasn’t there before could signal a surveillance device. The rest of this guide covers both scenarios, starting with the far more common one: insects.
Recognizing Signs of an Insect Infestation
Insects rarely announce themselves. Most infestations begin quietly and build for weeks before you notice. The physical evidence they leave behind is often more reliable than spotting the bugs themselves, since many household pests are nocturnal or hide deep inside walls and furniture.
Here’s what to look for:
- Droppings. Small roaches produce feces that resemble coffee grounds or black pepper. Larger roaches leave behind cylindrical pellets. Bed bugs leave dark or rusty spots of excrement on sheets, mattresses, and nearby walls.
- Frass. Drywood termites push tiny fecal pellets out of their tunnels. These look like small piles of coarse pepper or fine wood shavings, usually found beneath infested wood.
- Shed skins and egg cases. Bed bugs leave translucent shed exoskeletons near their hiding spots. Cockroaches produce oval-shaped egg cases called oothecae, often tucked behind furniture or wedged between books on a shelf.
- Gnaw marks. Rodents and some insects leave visible damage to wood, cardboard, and food packaging.
- Unusual smells. A musty, sweet odor can indicate a large bed bug population. A greasy or oily smell in a kitchen often points to cockroaches.
Where Household Pests Hide
Insects gravitate toward warmth, moisture, food, and darkness. That means your inspection should focus on kitchens, bathrooms, basements, and bedrooms before you bother with open living spaces.
In the kitchen, pull appliances away from the wall and check behind the refrigerator, stove, and dishwasher. Look under the sink where plumbing enters the wall, since gaps around pipes are highways for roaches and ants. Open cabinets and inspect corners, shelf liners, and the undersides of shelves.
In bedrooms, strip the bed completely. Check the seams and piping of the mattress, the box spring (especially the fabric on the underside), and the joints of the bed frame. Bed bugs tend to stay within a few feet of where people sleep, so inspect nightstands, picture frames, and electrical outlet covers near the bed. Dark or rusty spots on sheets are one of the earliest visible signs.
In bathrooms and basements, look for silverfish, centipedes, and drain flies near standing water, leaky pipes, and damp grout. Termite evidence tends to show up along baseboards, window frames, and any wood that contacts the ground. Mud tubes running up a foundation wall are a strong indicator of subterranean termites.
Tools That Help You Detect Insects
A flashlight and a credit card (for scraping along crevices) will get you surprisingly far. But a few inexpensive tools can make detection easier, especially when you suspect bed bugs or other pests that are hard to spot with the naked eye.
Interceptor traps are plastic dishes designed to fit under bed posts. They work because bed bugs are poor climbers on smooth vertical surfaces. The bug climbs up the textured outer wall of the trap, drops into a moat-like channel, and can’t climb back out. Products like the ClimbUp interceptor use a light dusting of talc to make the inner walls slippery, while others like the Blackout detector rely on roughened plastic on the outside and smooth plastic inside. Place these under all four legs of your bed and check them every few days. Even a single trapped bug confirms an infestation.
For a more active approach, small monitor-style traps like the Volcano bed bug detector can be paired with a carbon dioxide source to mimic a sleeping person’s breath. A thermos or styrofoam cup filled with dry ice placed near the trap significantly increases catch rates. This technique is especially useful in rooms where you suspect activity but haven’t found direct evidence yet.
Sticky glue boards (the kind sold at hardware stores for mice and insects) placed along walls, behind appliances, and inside cabinets give you a passive census of what’s moving through your home at night. Check them after 48 to 72 hours.
Thermal imaging cameras can detect large insect colonies behind walls without any demolition. These cameras don’t see through walls, but they pick up temperature differences on the surface caused by activity behind it. Termite nests show up as hotspots because the insects release heat from their digestive processes, and their mud tubes hold moisture that creates irregular thermal patterns. Wasp nests, beehives, and other large clusters of social insects also generate enough heat to appear on a thermal camera. Consumer-grade thermal cameras that attach to smartphones start around $200 and can be worth the investment if you suspect a hidden colony.
Nighttime Inspection Techniques
Many household pests, including bed bugs, cockroaches, and silverfish, are most active between midnight and 5 a.m. If daytime inspections turn up nothing but you’re still finding evidence, set an alarm for 2 a.m. and do a quick check with a flashlight. Move quickly when you enter the room and shine the light along baseboards, countertops, and bed frames. Roaches scatter from light, so you’ll often catch them in the first two or three seconds before they disappear.
For bed bugs specifically, avoid moving to another room to sleep if you suspect them. Sleeping elsewhere just encourages the bugs to follow your carbon dioxide trail to a new location, spreading the infestation.
Finding a Surveillance “Bug” in Your Home
If your concern is a hidden camera or listening device rather than an insect, the search strategy is different but equally systematic.
Start with a physical sweep. Hidden recording devices are most often concealed inside everyday objects placed near areas where conversations happen. Common hiding spots include USB flash drives, wall chargers, power banks, smoke detectors, desk accessories, lamps, digital pens, and key fobs. If any object near a seating area or bedroom looks unfamiliar, inspect it closely. Check underneath tables, couches, and shelves, since these are common spots for adhesive-mounted recording hardware.
Pay special attention to anything plugged into power. Surveillance devices need electricity, so wall chargers, extension cords, and USB adapters that you didn’t place there deserve scrutiny. A charger that feels warm when nothing is connected to it, or one that has a tiny pinhole on its face, could contain a camera.
Using Your Phone to Scan for Devices
Many hidden cameras connect to Wi-Fi to transmit footage. A network scanning app like Fing lets you see every device connected to your home network. Open the app, run a scan, and look for devices you don’t recognize. Cameras often show up with generic manufacturer names or as unidentified IP devices. If you find something suspicious, you can disconnect it from your router’s admin panel and see if anything in the house stops working.
Your smartphone camera can also detect infrared LEDs used by night-vision cameras. Turn off all the lights, open your phone’s front-facing camera (which typically lacks an IR filter), and slowly scan the room. Infrared LEDs will appear as a faint purple or white glow on your screen that’s invisible to the naked eye.
When a Professional Search Makes Sense
For insects, calling a pest management professional is worth it when you find evidence (droppings, frass, shed skins) but can’t locate the source, or when DIY traps confirm an infestation you can’t control with over-the-counter products. Termites and bed bugs in particular are difficult to eliminate without professional treatment, and early intervention limits the damage.
For surveillance devices, a professional Technical Surveillance Countermeasures (TSCM) sweep uses specialized equipment to detect radio frequencies, cellular signals, and wired devices that consumer tools miss. This is the more reliable option if you have strong reason to believe your home is being monitored, since many modern devices operate on frequencies or use storage methods that a phone app won’t catch.