By the time someone sees a cockroach walking across a kitchen floor, the population has usually been established for weeks or months. Cockroaches are nocturnal, they avoid open space, and they spend the overwhelming majority of their time wedged into crevices nobody looks into.
Which means the useful signs are the ones they leave behind. Here is what to look for and where, in the order it tends to appear. If several of these turn up, roach control is the next step.
Droppings
The most reliable early sign, and the one most often mistaken for dirt.
Small species leave specks that look like coarse ground pepper or coffee grounds, scattered or in small piles. Larger species leave cylindrical pellets with ridges along the length, which distinguishes them from mouse droppings of similar size.
They gather where the roaches shelter rather than where they feed, which is why the floor looks clean while the inside of a cabinet does not. Check the backs and corners of cabinets and drawers, the underside of a sink, behind and beneath appliances, inside the motor compartment of a refrigerator, along the top edge of door frames, and inside the hinges of cabinet doors.
Quantity is informative. A few specks suggests a recent or small population. A visible accumulation means it has been running a while.
Droppings accumulate where roaches shelter, not where they forage.
Egg cases
An ootheca is a hardened capsule holding the eggs, and finding one is proof of breeding rather than a visitor.
They are small, roughly the size of a grain of rice or slightly larger, brown and purse shaped with a ridge along one edge. Some species glue them to a surface in a protected spot, which is why they turn up cemented under a shelf, behind a drawer, inside a cabinet joint or in a crevice near the floor.
Empty cases, split open along the ridge, mean a hatch has already happened. They persist for a long time, so finding them indicates how long things have been going on.
The smell
An established cockroach population produces a distinct odor, usually described as musty, oily or faintly sweet, and it comes from the pheromones and secretions they leave in harborage areas.
It is strongest close to where they shelter, so it is noticeable when you open a cabinet under a sink, pull out a bottom drawer or lean into the space beside a refrigerator, and it may be undetectable standing in the middle of the room. A persistent musty smell from one cabinet that cleaning does not fix is worth taking seriously.
The odor also transfers. Food packaging, utensils and dishes stored in an infested cabinet can pick it up.
Smear marks and shed skins
Smear marks appear where roaches travel repeatedly in damp conditions, as irregular dark brown streaks along horizontal surfaces, wall and floor junctions, and the edges of pipes. They are easiest to see on light surfaces in a basement or under a sink.
Shed skins. Cockroaches molt several times as they grow, leaving a pale translucent shell that keeps the shape of the insect. They collect in harborage areas alongside droppings, and because each individual sheds repeatedly, a quantity of them indicates a breeding population rather than a stray.
Both of these are the signs most often vacuumed away without being recognized, which is a shame because they are among the most informative.
Shed skins accumulate in harborage and look like hollow roaches.
Damage to food and packaging
Cockroaches chew into cardboard and paper readily, and cardboard is both food and shelter to them. Look for small irregular holes in cereal boxes, pasta boxes and pet food bags, and for packaging that has been gnawed along a glued seam.
They also feed on paper, book bindings, wallpaper paste and fabric with a food residue on it, so damage is not confined to the pantry.
Where to look, in order
- Under the kitchen sink, the single most productive location in most homes. Check the cabinet floor, the back corners, around the pipes and the underside of the sink basin
- Behind and underneath the refrigerator, including the condenser coils and motor housing, which are warm, dark and rarely cleaned
- Beside and under the stove and dishwasher, in the gaps where spills collect
- Inside cabinets and drawers, the back corners, the runners and the undersides
- Behind a microwave or toaster, and inside small appliance housings
- Around the water heater and any utility sink
- Floor drains, sump areas and around basement pipework
- Behind loose trim and in gaps around pipe penetrations
Seeing one in daylight
Because cockroaches avoid light and prefer tight crevices, one out in the open during the day is a meaningful signal rather than bad luck.
It generally means the sheltered space is crowded enough that individuals are being pushed into less desirable areas, which implies a substantial population rather than a handful.
The same goes for seeing several at once when a light goes on at night. A scatter of roaches across a counter is a late stage sign. What to do when you see one covers the right response.
Daytime activity in the open usually means the harborage is crowded.
Why it matters beyond the nuisance
Two reasons this is worth catching early rather than tolerating.
Cockroaches move between drains, waste and food surfaces, picking up and depositing bacteria along the way, which makes contamination of food preparation areas a genuine concern rather than a squeamish one.
And their saliva, droppings, shed skins and body fragments are a recognized asthma trigger, particularly in children. In a household with asthma, an established population in a kitchen is a health issue in its own right.
What to do if you find the signs
- Note where, which tells a technician the extent and the likely harborage
- Fix every leak and dry out condensation, since water matters to them more than food
- Clean the hidden food sources: appliance gaps, grease films, the bottoms of trash cans, pet food, recycling
- Remove cardboard and clutter, which is both shelter and food
- Do not fog or spray broadly, which scatters the population into voids and undermines bait
- Get an inspection rather than guessing at the extent, since what is visible is a fraction of what is there
Stewart Termite & Pest Control has dealt with cockroach problems in Pittsburgh homes and businesses since 1987. Call 412-822-7610 or request an estimate online.
Frequently Asked Questions
What are the first signs of a cockroach problem?
Droppings that look like coarse pepper or ridged pellets in cabinet corners and under sinks, shed skins, purse shaped egg cases glued into crevices, and a musty odor from an enclosed space.
Where should I look for cockroach signs?
Under the kitchen sink first, then behind and under the refrigerator, beside the stove and dishwasher, inside cabinet and drawer corners, and around the water heater and basement pipework.
What do cockroach droppings look like?
Small species leave specks like ground pepper or coffee grounds. Larger species leave cylindrical pellets with ridges along the length, which separates them from mouse droppings.
What does a cockroach infestation smell like?
Musty, oily or faintly sweet, strongest when you open a cabinet or lean into the gap beside an appliance. It comes from pheromones and secretions in the harborage area.
Does seeing a cockroach during the day mean a big problem?
Usually. They are nocturnal and prefer tight crevices, so daytime activity in the open suggests the sheltered space is crowded and the population is substantial.
Are cockroaches a health risk?
Yes. They carry bacteria between drains, waste and food surfaces, and their droppings, saliva and shed skins are a recognized asthma trigger, particularly in children.