It is a diverse family with many genera and hundreds of species. Those classified as Periplaneta and Blatta are widely distributed, whereas other genera are more regional. They are large insects that tend to live outdoors. Several species are referred to locally as palmetto bugs.
There are five or six species belonging to the genus Periplaneta (Blattidae) (pictured above) that are important pests. The American cockroach, P. americana, is the most notorious. It measures 35– 40 mm in length and is a chocolate-brown color in all stages. Adults of both sexes are fully winged and may undertake a weak flight.
It is widely distributed around the world, but does not extend into the temperate zones as far as does the German cockroach. It requires 6 –9 months to complete its life cycle. Among other Periplaneta species of importance are the Australian cockroach, P. australasiae, the smoky-brown cockroach, P. fuliginosa, and the Japanese cockroach, P. japonica. They each have a more restricted distribution. The latter species, for example, is found in Japan and China.
They are all large cockroaches with a long life cycle, but can become numerous under certain conditions. They tend to be outdoor cockroaches, but often occupy buildings in which food is stored, prepared, or served. Extract from Encyclopedia of Insects Vol 2. Vincent H. Resh, Ring T. Cardé