Reviewed by William "Willy" Vizcarrondo, NYS DEC Certified Commercial Pesticide Applicator C1825832. Updated September 23, 2026.
Short answer
No. German cockroaches don't come in from outside; the University of Florida's extension notes they're spread entirely by people, in grocery bags, cardboard, used appliances and furniture, and between apartments through shared walls. A clean kitchen makes them easier to control, but it doesn't keep them from arriving, and a few crumbs behind the refrigerator is all they need to stay.
They're carried. UF IFAS is specific that German cockroaches do not enter structures from outdoors and live only in association with people, so every kitchen infestation started with something coming through the door: a case of soda from a warehouse, a delivery box, a used microwave, a bag from a store that has them, a piece of secondhand furniture, or the plumbing wall you share with the apartment next door. That's why spotless houses get them and why they're so common in multi-unit buildings. The bigger outdoor roaches are different, coming in through drains and gaps, but they're not a cleanliness problem either.
Food, water and hiding places, in tiny amounts. UF IFAS calls it the survival triangle: food, water and harborage. A roach lives on grease on the side of a stove, crumbs in a toaster, pet food left down overnight, the drip under a sink trap and the condensation on a cold water pipe, and it hides in the gap between the counter and the wall, the cabinet hinge, the dishwasher insulation and the seam of a cardboard box. You can mop every night and still be feeding them. UC IPM's sanitation list is about cutting off exactly those things: store food in sealed containers, eliminate water sources, and remove clutter, cardboard and trash.
Because the population is already established in places you can't clean. UC IPM's position is that pesticides alone will not solve a cockroach problem, and the reverse is also true: sanitation alone won't either, because roaches hidden in wall voids and appliance housings keep breeding on what little they find, and UC IPM notes one female and her offspring can produce over 30,000 individuals in a year. What works is the combination: sanitation to make bait the best food available, gel bait placed in the harborages so they eat it and carry it back, and follow-up. UC IPM notes it can take 7 days or longer before you see fewer roaches, and it warns against foggers and aerosol sprays, which scatter them to new rooms.
The homes we treat for German cockroaches in Hempstead, Freeport, Valley Stream, Long Beach and Queens are as often immaculate as not. What they have in common is a source: a shared wall, a delivery, a used appliance. Bobby Bugs uses gel bait in the harborages and doesn't fog, and we'll show you the handful of spots, behind the stove, under the sink, at the dishwasher, where a wipe-down every few days does more than a whole-house scrub. German cockroach work carries a 60-day written guarantee.
Related
Yes, easily. In attached houses and apartments German cockroaches travel along plumbing lines and through gaps around pipes, outlets and baseboards on shared walls. Your unit can be spotless and still get them from next door, which is why building-wide treatment works better than one apartment at a time.
A health problem. UC IPM notes indoor cockroach infestations are important sources of allergens and have been identified as risk factors for the development of asthma in children, especially in multi-unit housing. They also walk from drains and garbage to food surfaces.
No food or water available overnight. That's when roaches forage. Dishes done, counters and stovetop wiped, pet bowls picked up, sink dry, trash out or lidded. It won't remove an infestation, but it makes every bait placement work faster.
Still not sure? Call (516) 509-6001 and we'll tell you what you're dealing with.