There are a great variety of roach species in the world, though not all of them are pests. The most famous of course are the pest species, including the most common domestic cockroach in the U.S, the German cockroach, (_Blattella germanica_), and the second most common, the American cockroach (_Periplaneta americana_), both the main subjects of the book. Other pest species in North America include the oriental cockroach, brown-banded roach (noted for colonizing appliances), and the smokey-brown, though there are 64 other species on the continent far from the haunts of man. More than 5,000 species of cockroach are known in the order Blattaria (from the Greek word blattae, for roach). Only about a hundred species worldwide occur around humans at all; most live unseen, generally in hot humid jungles though they are found virtually everywhere on Earth.
Thy say that cockroaches will survive the atom bomb. Go figure!