The most common roach is the German cockroach. You can mostly find this pest in kitchens and bathrooms and just about any place where people eat and drink. It has been implicated in outbreaks of illness and reported to propagate at least 33 kinds of bacteria, six types of worms, and seven other human pathogens. The allergens it spreads can be linked to asthma attacks in children.
The Oriental cockroach is often found in sewers and under debris, leaves, stone, and firewood. It also lives around voids and openings beneath porches before invading homes in the summer.
The American cockroach is the type to invade a property when food shortages occur. It likes warm, dark environments and will come up from sewer drains and pipework.