They can be found in yards, beneath leaves, in dumps, in crawlspace, in the mulch of flower beds, or in landscape retaining walls. They are also common in high-moisture areas such as sewer, water meter enclosures, drains and dark damp basements. They are commonly found in bathtubs because they have difficulty walking on or up smooth surfaces due to their small tarsal pads.

Oriental cockroaches are sometimes called "waterbugs" by people who don't realize they are a type of cockroach. This nickname reflects their affinity for humid, moist locations. Oriental cockroaches differ from the other three species, because it can live outdoors in the northern U.S. Outdoors, oriental cockroaches are found where there is high organic matter, like wood chips or mulch, between soil and the foundation, underneath patio bricks and sidewalks. They sometimes aggregate under garbage cans. During hot, dry periods, they may move indoors to find locations more moist and humid. Indoors, they will be found in basements, especially in cool, damp locations like bathrooms and floor drains. Crawlspaces may be infested with oriental cockroaches which may invade homes.

Oriental cockroaches feed on all kinds of filth, rubbish, and other decaying organic matter. They seem especially fond of garbage and the contents of discarded tin cans. If water is available, they can live for a month without food; without water they die within two weeks. The most important aspect of cockroach damage derives from their habit of feeding and harboring in damp and unsanitary places such as sewers, garbage disposals, kitchens, bathrooms, and indoor storage areas. Filth from these sources is spread by cockroaches to food supplies, food preparation surfaces, dishes, utensils, and other surfaces. Cockroaches contaminate far more food than they are able to eat.

• Cockroaches have many negative consequences for human health because certain proteins (called allergens) found in cockroach feces, saliva and body parts can cause allergic reactions or trigger asthma symptoms, especially in children.
• Cockroaches can also passively transport microbes on their body surfaces including pathogens that are potentially dangerous to humans. Cockroaches have been implicated in the spread 33 kinds of bacteria, including E. coli and Salmonella species, six parasitic worms and more than seven other types of human pathogens.
• E. coli and Salmonella are classic causes of food poisoning, or gastroenteritis. Common symptoms include belly pain, severe stomach cramps and tenderness, diarrhea which can sometimes be bloody, nausea and vomiting. Some people can experience severe diarrhea, which will cause dehydration and may require hospitalization. In rare cases, the bacteria can spread to the blood stream and cause life threatening infections.