Moisture sources also are kitchen and bathroom sinks, leaky dishwashers and bathtubs. Steps should be taken to minimize excess moisture buildup in each case, even if this means drying out sinks and bathtubs after use. Although the elimination of water sources is the simplest goal of the three, in theory, it is often the most difficult to achieve, because leaky pipes in wall voids cannot be detected by the homeowner. The third critical element for cockroach survival in a home is harborage. By nature, cockroaches run from the light.
Cockroaches prefer dark, tight, warm, and moist places.
The elimination of harborages is important in controlling infestations. Any small gap or hole that leads to a void is a prime cockroach harboring area and must be sealed. Uncluttering what is cluttered removes potential harboring areas from cockroaches, so keep all areas of the home, especially the kitchen, uncluttered and free of useless debris. Outside, remove cluttered debris and trash from around the house. Stack firewood well away from the house, as this is a prime harborage area for large cockroaches.