People often assume roaches appear because a home is dirty. That is not accurate. Roaches are opportunistic survivors that have been on this planet for 320 million years. They are extraordinarily good at finding food, water and shelter. Understanding their biology tells you exactly how they get into your home and how to stop them.
How Roaches Enter Your Home
Hitchhiking The most common way roaches enter a home is by hitchhiking inside boxes, bags, used furniture and appliances. A single female carrying an egg case can establish an entire infestation. This is particularly common with grocery bags, cardboard boxes from stores and second-hand furniture.
Plumbing and drainage Roaches are capable of surviving underwater for up to 30 minutes and can travel through drain pipes. American cockroaches in particular are commonly found entering homes through floor drains, sink drains and toilet pipes from the sewer system.
Gaps and cracks German cockroaches, the most common indoor species, can squeeze through a gap as thin as 1.6 millimeters. That is the thickness of two stacked credit cards. Common entry points include gaps around pipes where they enter through walls, spaces under exterior doors, gaps around window frames and cracks in the foundation.
Neighboring infestations In multi-unit buildings, roaches travel freely through shared walls and plumbing. A neighbor's infestation becomes your infestation.
Why Roaches Choose Your Home
Roaches need three things: food, water and warmth. Your kitchen provides all three. Crumbs under appliances, moisture from the sink, warmth from the stove and refrigerator motor, and the dark confined spaces behind and under everything create a near-perfect roach habitat.
Bathrooms are the second most common location because of the consistent moisture, warmth and dark hiding spaces behind toilets, under vanities and around pipes.
The Biology of an Infestation
A single female German cockroach produces an egg case every 3 to 4 weeks containing 30 to 40 eggs. Those eggs hatch in about a month. The offspring reach reproductive maturity in 6 to 12 weeks. In ideal conditions, a single female can be responsible for over 400 descendants in one year.
This exponential growth rate is why infestations that seem to appear suddenly have almost always been building for months in hidden locations.
What to Do
Knowing how roaches enter your home allows you to both treat current infestations and prevent future ones. Seal gaps around pipes, install door sweeps on exterior doors, inspect second-hand items before bringing them inside and treat the areas where roaches nest and travel with professional-grade gel bait.