Why do I see roaches in a clean house?

Because a clean house still gives cockroaches what they need: cockroaches can survive anywhere they can find food, water and shelter, and they forage at night and eat a wide variety of foods and non-food materials, which lets them survive even in tidy homes.^[1] Seeing them is not a judgement on your housekeeping. It usually means one of a handful of things below.

1. They came in from somewhere else

Cockroaches get into homes by riding in on grocery bags or other containers, crawling in from outdoors, and moving from one apartment, duplex or condo unit to another through the plumbing and other holes in shared walls.^[1] Secondhand furniture and items kept in storage should be inspected before they come inside too.^[2] If you share walls with neighbours, their roaches can become yours however clean your kitchen is.

2. It is an outdoor roach that wandered in

Not every roach indoors lives indoors. Wood roaches are native insects found throughout Virginia, living in leaf litter, rotting wood, wet mulch, clogged gutters, firewood piles and under loose siding.^[3] Adult males may be attracted to bright porch lights at night, and houses built in heavily wooded areas may have more wood roaches than houses away from woods.^[3] When one gets inside, they die within days for lack of moisture and cannot survive or reproduce indoors.^[3] Unlike most cockroaches, they may be seen blundering around during the day.^[3]

Thick layers of wood mulch around foundations encourage cockroach populations, which may move indoors in colder weather.^[2] A roach that turns up in the basement in autumn may have come in from outside.

3. There is water you have not noticed

Cockroaches must have a source of water to survive,^[2] and a clean kitchen can still have a slow drip under the sink, a sweating pipe, or leaks or condensation at sinks, toilets, water heaters, air conditioners, water pipes and faucets.^[2] Look in the cabinet under every sink, behind the toilet, around the water heater and under the refrigerator.

Drains are a common way in. Cockroaches can enter through dry drains,^[2] and the drain in a guest bathroom or a basement floor drain that is never used can dry out and leave an open path.

4. There is food you cannot see

Cockroaches eat far more than leftovers, including plant matter, dead insects, garbage and materials soiled with starches or oils.^[2] In a tidy home the usual sources are accumulated cooking grease around the stove and other appliances,^[2] crumbs that fall into the gap beside the stove, pet food left out overnight, a toaster, and recycling that was not rinsed.

5. There are hiding places close to food and water

Tight cracks 3/8 inch or smaller are suitable hiding places,^[4] so gaps behind cabinets, along baseboards and around pipes are enough. Clutter matters more than dirt: unused cardboard boxes, stacks of papers and piles of laundry provide ideal shelter.^[2] Some species prefer to hide inside electronics and small appliances.^[2] Once a few roaches settle, pheromones in cockroach droppings attract more cockroaches to the same runways and hiding places.^[2]

How to tell a visitor from an infestation

Cockroaches are primarily nocturnal, so you may find dead cockroaches, egg cases, cast skins or droppings before you see a live one, and seeing more of them during the day may indicate a large, growing infestation.^[2] A single roach that turns up once, with no droppings or egg cases, is likely a visitor. Small roaches in the kitchen, repeated sightings, or dark specks and smears of droppings in cabinet corners suggest roaches breeding inside.

Sticky traps settle the question. Put several under sinks, behind appliances and along cabinet bases and check them daily. Traps that stay empty suggest an occasional visitor, though roaches hide well, so keep a few out and keep looking; regular catches show you where they live and where to treat.

Avoid reaching for a spray at the first sighting. Some pesticide sprays repel cockroaches rather than kill them,^[1] which can chase them into other rooms or apartments.^[4] For what to do once you know they live inside, see how to get rid of cockroaches.

If you rent

Tell your landlord even if your unit is spotless. Virginia tenants must promptly tell the landlord about insects or pests, and a tenant can be charged the added cost of treatment caused by an unreasonable delay in reporting.^[5] Roaches coming from another unit need a building-wide answer, covered in how to keep cockroaches out of an apartment.

Stop and call a pro if

• Traps catch roaches night after night, or you see them in daylight.
• You find egg cases, droppings or small nymphs in the kitchen or bathroom.
• They are coming through shared walls or plumbing from another unit.
• You have fixed the water, food and drain problems and they keep returning.
• Someone in the home has asthma or allergy symptoms. Cockroach secretions, droppings and body parts can trigger allergies and asthma in some people.^[2]

Getting help on Loclis

Read whether you can handle cockroaches yourself or need an exterminator, browse cockroach control services, find pest control around Blacksburg or see more pest control answers. When you are ready, describe the job on Loclis so licensed pest control businesses can quote it.