- Infestations caused by unsanitary conditions -

Summary: Cockroaches (aka "roaches") are probably the most important pest in structures where food is prepared, such as homes and restaurants, worldwide. Cockroaches are experts at finding and exploiting whatever food scraps we leave for them. They are generally, but not always, associated with unsanitary conditions.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

Cockroaches are common household pests

Cockroaches are medium to large, light brown to black insects that are probably the most important structure-infesting pest worldwide. Most people think of roaches as associated with unsanitary urban environments but many species never enter buildings at all. Those species that do invade dwellings are called peridomestic. The following pages will help you get rid of peridomesic roaches from home kitchens and commercial property such as apartment buildings and restaurants. There are only a few pest species and these are relatively easy to tell apart (see How to Tell Pest Cockroach Species Apart).

picture of German roach

German roach (adult) about 5/8" (16mm) long; note long antennae and dark stripes behind the head

Cockroaches that infest buildings require a relatively warm and moist environment. Besides a place to live these pests need to find food and water. Almost any food can attract and support these scavengers, and infestations can grow very quickly. While roaches do not cause structural damage their presence often indicates unsanitary conditions that may be unhealthy. There are also concerns about them directly causing allergic reactions and spreading disease by contaminating food.

Roaches do not form true colonies the way termites and ants do but they often live in groups. They prefer warm and damp areas in out-of-the-way protected places, such as inside walls, called harborages. Roach activity is usually highest at night. In fact, any activity in the open, during the day typically indicates very high populations with individuals actually pushed out of harborages because of overcrowding. Therefore, if you see cockroaches during the day it usually means that the infestation is fairly large.

Roach control

Getting rid of roaches in a single-family home is relatively easy but control of infestations in a large apartment building, or commercial building, is much more difficult. The difference is that homeowners can clean and treat every room. On the other hand, in large multi-family and commercial buildings there are often areas that are not treated.

In either case effective roach control must include elimination of food and water sources and treatment with special baits and insecticides, see Cockroach Control and Professional Baits. A wide variety of baits, traps and insecticides for cockroach control are available here (, our affiliate).

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