Their shape enables them to use tiny cracks as hiding places. They are popularly believed to be carriers of human diseases, although this has not been proved. The large, dark Oriental cockroach, Blatta orientalis, is a cosmopolitan household species. The smaller German cockroach, or Croton bug, Blattella germanica, native to Europe, is the common urban cockroach of the NE United States. The American cockroach, Periplanata americana, is a large light-reddish species that invades houses in the S United States.
Cockroaches reproduce sexually.
Their eggs are encased in capsules called oothecae, which in some species remain attached to the abdomen of the female until the eggs hatch. In a few species the ootheca is retained within the body of the female and the young are born live. Young resemble the adults except in size. These ancient cockroaches were able to fly and were probably the first flying animals. Cockroaches are classified in five families of the phylum Arthropoda , class Insecta, order Orthoptera, suborder Blattaria.