As with all pests, identification is the key to control. Here are descriptions and a key to identifying late-instar cockroach nymphs.
A prime ingredient to successfully controlling any pest is identification. Knowing which species is causing the problem will provide clues to where it harbors and what conditions make it possible for that species to survive. This information is critical for designing a targeted control program that reduces both insecticide application and callbacks.
Although there are more than 3,600 species of cockroaches, less than two dozen are considered pests. Most cockroaches live in forests, where they feed on decaying organic matter and serve as a source of food for many small animals and birds with whom they share their environment. In North America, there are about 12 cockroach species that are a nuisance because they live in and around homes and other structures.
The key presented on page 100 is for a group that traditionally has been very difficult to identify — late-instar cockroach nymphs (Hathorne and Zungoli 1999). The 12 species included represent three families of cockroaches — Blattellidae, Blattidae and Blaberidae. Many of these species look similar at first glance, but each has a unique characteristic that separates it from the others. The terms used for identification are labeled on the generalized drawing of the cockroach nymph that appears on the key. The identifications are only appropriate for late-instar cockroach nymphs.
To view the key to late-instar cockroach nymphs click here:http://www.pctonline.com/articles/images/maycockroachquiz3.pdf
1. German cockroach — Blattella germanica (L.) — The German cockroach is the most common cockroach pest in the world and it is the most important pest species in the U.S. It requires moisture daily and is common in areas with easy access to water or with poor sanitation. The German cockroach is not found outdoors and does not fly as an adult.
2. Asian cockroach — Blattella asahinai Mizukubo — The Asian cockroach was first recorded in the continental U.S. in 1986 in Florida. It is now found in South Carolina and may be in other southeastern states. While the Asian and German cockroaches look alike, their behavior is quite different. The Asian cockroach is a good flier as an adult and is found primarily outdoors. It is attracted to light. Outdoors, they are found resting in leaf litter, grassy areas and in trees.
3. Field cockroach — Blattella vaga Hebard — The field cockroach is rarely a pest in buildings. It was introduced into the southwestern United States and also is reported from southeastern Texas and southwestern Louisiana. It is often found in irrigated fields and yards and is attracted to decomposing plant material. It also thrives in arid areas. Unlike other cockroaches, the field cockroach usually is not found living close to others of its kind. They tend to be more solitary than other cockroaches.
4. Broad wood cockroach — Parcoblatta lata (Brunner) — The broad wood cockroach is found outdoors in wooded areas in the mideastern U.S. and along the Atlantic Coast to Connecticut. Adult females are wingless and live most of their lives in fallen trees or under bark or rocks where they feed and deposit eggcases. Males are good fliers. They are attracted to light at night and may enter homes through doors or windows. Females live away from structures so infestations are not likely indoors.
5. Brownbanded cockroach — Supella longipalpa (F.) — The brownbanded cockroach was first recorded in Florida in 1907 and is now found throughout the United States. It prefers temperatures higher than 80 degrees and often rests close to the ceiling. It will infest furniture and appliances and deposit egg cases in these items as well. It does not have a high moisture requirement and frequently is found where sanitation is relatively good, like in office buildings. It is not found outdoors.
6. American cockroach — Periplaneta americana (L.) — The American cockroach is found throughout the United States and is associated with buildings and warm, humid situations both in and outdoors. It is often found in sewers, steam heat tunnels and greenhouses.
7. Australian cockroach — Periplaneta australasiae (F.) — The Australian cockroach is found in and outdoors in Florida. While it may be found in northern states, it is only associated with protected environments like greenhouses and steam heat tunnels.
8. Brown cockroach — Peripaneta brunnea Burmeister — The Brown cockroach is found around buildings in the Southeast United States, but not in natural habitats. It is more elusive than other species in this group. It is only rarely found indoors and it is often confused with the smokybrown cockroach.
9. Smokybrown cockroach — Periplaneta fuliginosa (Serville) — The smokybrown cockroach is found in the southeastern states and parts of California. It survives well in hot, humid areas in and around structures. When established indoors, infestations often are found in attics.
10. Oriental cockroach — Blatta orientalis (L.) — The oriental cockroach is found throughout the temperate areas of the United States and Canada. It lives in and around buildings and also is associated with garbage areas, sewers and poultry facilities. It prefers cooler, damper habitats like crawl spaces and basements.
11. Florida woods cockroach — Eurycotis floridana (Walker) — The Florida woods cockroach is found in peninsular Florida and the lower Gulf and Atlantic Coast states. It is found in natural and peri-domestic habitats.
12. Cuban cockroach — Panchlora nivea (L.) — This roach is found in Florida and along the Gulf Coast of Louisiana and Texas. It is found in areas with high humidity and is attracted to light as an adult.
REFERENCE: Hathorne, K. and P. Zungoli. 1999. Identification of Late-Instar Nymphs of Cockroaches (Blattodea). Proc. Entomol. Soc. Wash. 101 (2): 316-324.
The authors are a lab technician and a professor of entomology, respectively, at Clemson University. Pat Zungoli can be reached via e-mail at email@example.com.