How do cockroaches get in the house?

People mistakenly believe that cockroaches only infest dirty houses. Unfortunately, cockroaches are equal-opportunity invaders. Even spotlessly clean houses can attract cockroaches. These pests can carry disease and can cause food poisoning and trigger allergies and even asthma attacks as a result of the dander of discarded exoskeletons and feces.  

Where do cockroaches come from?  Cockroaches in your house may have already been there when you moved in. Roaches are also easily transported from infested dwellings to new places, so they may have moved with you from your previous home. They may come from your neighbor’s property, or they may enter your house from their outside habitat.

How do roaches get in the house? Two species of roaches get in the house by hitchhiking in grocery bags, cardboard boxes, luggage or furniture. You may bring a pregnant German or brown-banded cockroach (or an egg case) home in a grocery bag or cardboard box, so always inspect those containers. Check food for roaches before putting it away, and store your grocery bags outside. Get rid of empty corrugated boxes immediately, because these can be a favorite breeding ground for roaches. If you work in a cockroach-infested building, you could easily carry them home. Your children may carry cockroaches home from school in their backpacks or lunch containers, so check them every night.

Roaches can also get in the house through the plumbing. They migrate between apartments by traveling along the plumbing within a common wall. To prevent this migration, seal holes in common walls and around plumbing pipes. Oriental cockroaches enter buildings from their outside habitat by moving along plumbing pipes, usually up through the floor from underneath the crawl space, and under door or window jambs. Use window screens and seal openings around doors and windows to keep the cockroaches outside.

Sewers or drains are other cockroach entry points. Repairs on the sewer system may lead to displaced American cockroaches entering buildings. Seal or use screens for large openings around outside drainage lines and sewer vents. Use tightly packed steel wool as a temporary filler until the openings can be sealed properly.

Where are roaches found? German cockroaches are the most common indoor roaches, particularly in multifamily residences. German cockroaches prefer dark, warm, humid places near food and water, where the temperature is 70 to 75° F. They’re usually found in kitchens, in cracks and crevices of cabinets, near sinks or appliances or in food preparation and storage areas. They’re also commonly found in the bathroom. To help control German cockroaches, clean up spilled food and crumbs, and don’t leave dirty dishes overnight. Store food in airtight sealed containers. Put garbage in a sturdy container with a tightly fitting lid.

Oriental cockroaches prefer cool, damp, dark places. Outdoors you’ll find them in areas where there’s organic matter such as mulch and woodchips, underneath patio bricks and sidewalks and between soil and the foundation. Indoors you’ll find them in sewer drains, basements and crawl spaces or on the lower floors, especially in bathrooms and drains. You may also see them near leaky water pipes and under sinks, refrigerators, washing machines and floors.

Brown-banded cockroaches prefer warmer (greater than 80° F), drier places than German cockroaches. They live in high areas, at eye level or above, hiding in cabinets and pantries, closet shelves, behind pictures, among books, underneath kitchen chairs and tables and in shower stalls. You’ll also find them in warm areas near electric clocks, timers, televisions and refrigerator motors. You may see their egg cases on your walls, textured ceilings or furniture or near the kitchen sink.  

American cockroaches are often found within homes and are known to commonly inhabit restaurants, grocery stores and bakeries—anywhere food is prepared and stored. They prefer warm, moist areas and are commonly found in boiler rooms, heated steam tunnels, basements, around pipes and water heaters and wet floor drains. They are common in sewer systems.