There are six species of cockroaches in California that can become pests: German cockroach, brownbanded cockroach, oriental cockroach, smokybrown cockroach, American cockroach, and Turkestan cockroach. A seventh species, the field cockroach, is not really a pest. It is usually found outdoors, but sometimes comes indoors when it is hot or dry and is often mistaken for the German cockroach. Of these seven species, the one that has the greatest potential for becoming persistent and troublesome is the German cockroach, which prefers indoor locations. Oriental and American cockroaches occasionally pose problems in moist, humid areas.
PROBLEMS ASSOCIATED WITH COCKROACHES
Cockroaches may become pests in homes, schools, restaurants, hospitals, warehouses, offices, and virtually in any structure that has food preparation or storage areas. They contaminate food and eating utensils, destroy fabric and paper products, and impart stains and unpleasant odors to surfaces they contact.
People are repulsed when they find cockroaches in their homes and kitchens. Cockroaches (especially the American cockroach, which comes into contact with human excrement in sewers or with pet droppings) may transmit bacteria that cause food poisoning (Salmonella spp. and Shigella spp.). German cockroaches are believed to be capable of transmitting disease-causing organisms such as Staphylococcus spp., Streptococcus spp., hepatitis virus, and coliform bacteria. They also have been implicated in the spread of typhoid and dysentery. Indoor infestations of cockroaches are an important source of allergens and risk for asthma among some populations. The levels of cockroaches and allergens are directly related to cockroach density, housing disrepair, and sanitary conditions.
Cockroaches are medium-sized to large insects in the order Dictyoptera (formerly Orthoptera). They are broad, flattened insects with long antennae and a prominent, shield-shaped section behind the head called a pronotum. Some people confuse them with beetles, but adult cockroaches have membranous wings and lack the thick, hardened forewings (elytra) of beetles. They are nocturnal and have a tendency to scatter when disturbed. Immature cockroaches (nymphs) look like adults, but are smaller and do not have wings.
Of the six common pest species, German and brownbanded cockroaches inhabit buildings, whereas the oriental, smokybrown, American, and Turkestan cockroaches usually live outdoors or in masonry enclosures away from buildings, only occasionally invading buildings themselves. It is important to correctly identify the species involved in a cockroach infestation so that the most effective control method(s) may be chosen.