Species: Periplaneta americana (Linnaeus)
AKA: Palmetto bug or water bug
The American cockroach is a large cockroach. The adult body length is approximately 1-1/2 inches long (38mm). The antennae extending from the head are equally as long as the body if they are intact.
The adult is a shiny reddish brown to dark brown and has a yellow margin on the pronotum (region directly behind the head). Immature American cockroaches (nymphs) are also reddish brown to dark brown in color. Large nymphs often have yellow markings on the abdomen.
Adult American cockroaches have wings and will occasionally fly. However, they are awkward fliers and prefer to run when disturbed. Male and female American cockroaches are about the same size and look very similar. Both have a pair of cerci, finger-like appendages, at the tips of their abdomens. The cerci are used to detect air movement in the cockroach’s surroundings. Male cockroaches have an additional set of appendages called styli on their abdomens. The styli are located between the cerci but are smaller and more delicate. The presence of styli is the easiest way to distinguish male from female cockroaches. Immature American cockroaches resemble adults, except they are smaller and wingless. The American cockroach egg capsules are mahogany brown and about 1/3 inch long. The egg capsules resemble small ridged purses (Figure 2) and are often stuck to the outside of boxes, or along baseboards in locations where the cockroaches are infesting.
American cockroaches are a “peridomestic species.” This means that they generally live outdoors. However, populations can also move indoors and live in human structures. American cockroaches usually live in warm, moist, humid environments but can survive in drier areas if they have access to water. The cockroaches prefer temperatures between 70°F and 85°F and will not survive if temperatures drop below 15°F. In structures, American cockroaches are common in areas where food is prepared or stored and moisture is plentiful. They are frequently found in restaurants, grocery stores, and bakeries. They are also associated with commercial kitchens, boiler rooms, sewers, and steam tunnels. In and around residential or commercial buildings, American cockroaches usually infest basements, crawl spaces, bathrooms, and decorative landscaping. Indoor populations tend to forage outdoors during warm weather. Similarly, during the winter months, outdoor populations may move inside seeking warmth and moisture.
After becoming an adult, a female American cockroach will mate and produce an egg case in 3 to 7 days. She will carry the egg case protruding from the tip of her abdomen for another two days. The egg case will then be deposited in a hidden location and glued to a surface with the female’s saliva. Hiding the egg case helps to protect it from predators, parasites, and pest technicians. Each egg case contains an average of 14 embryos. The immature cockroaches will emerge in 24 to 38 days in warm conditions. The juvenile cockroaches will go through 7 to 8 molts before they become mature. Molting involves the periodic shedding of the exoskeleton in order to grow larger. Recently molted cockroaches will be completely white in appearance, causing some people to believe that there are albino cockroaches. However, the bodies of these recently molted individuals will harden and darken within a few hours. American cockroaches will complete their development and become reproductive in six to 12 months. Adult American cockroaches can live approximately a year to a year and a half. An adult female American cockroach will produce a new egg capsule about every 9 days, resulting in the production of between 25-30 egg cases during her adult life.
American cockroaches feed on a wide variety of materials, including cosmetics, beer, potted plants, wallpaper paste, soap, postage stamps, fermenting fruit, pet food, and human food. They contaminate human food, clothing, paper goods, and surfaces with their feces and body parts. American cockroaches also produce a strong unpleasant odor. This characteristic odor is not only detectable in infested buildings but is also transferred to items that the cockroaches crawl across when foraging. A pest management professional can often detect an American cockroach infestation by smell before he has actually seen any cockroaches.
When American cockroaches aggregate (Figure 3), their presence is primarily an aesthetic nuisance. However, members of this species are also known to carry infectious bacteria on their bodies and in their gut. These bacteria may be transferred to food and other items that the cockroaches contact. Several bacteria commonly associated with American cockroaches are known to cause food poisoning, dysentery, and diarrhea in humans. However, it should be noted that American cockroaches have never been implicated as the cause of any disease outbreak, so while American cockroaches are known to carry disease organisms, they are not a major disease health threat. Yet, American cockroaches also produce allergens on their bodies and in their fecal material. While American cockroaches are not considered to be major culprits of human allergies or respiratory problems like some other cockroach species, they have been implicated as a potential cause of allergic dermatitis and childhood asthma.
The best method for controlling American cockroaches is to keep them from establishing an infestation in the first place. Therefore, prevention methods are the first line of defense when dealing with American cockroaches.
American cockroaches are significant pests throughout the world. However, they are not native to the Americas at all. The original home of the American cockroach is actually tropical Africa. Evidence indicates that the American cockroach was transported to the Americas on slave ships.
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
March 4, 2010