There are no ‘wild’ populations of German cockroaches. They exist only in association with humans. Therefore, German cockroaches are the most common cockroach pest found in homes, restaurants, grocery stores, correctional facilities, schools, and other buildings where food is stored or prepared. German cockroaches are transported easily in clothing, bags, boxes, and other belongings. German cockroaches have strict moisture requirements so infestations generally develop in kitchen and bathroom areas. Cockroaches often take up residence in warm cracks and crevices that are within five feet of a water source. Cockroaches aggregate behind refrigerators, picture frames, and clocks or in cabinets, drawers, stoves, and dishwashers. German cockroaches spend about 75 percent of their time in these safe harborage areas. If cockroaches are seen aggregating in corners of the ceiling or other locations out in the open, it is a sign that the infestation has reached such a high level and that there are no secluded cockroach harborages available.