Among the best-known plague species are the American cockroach. Periplaneta Americana. which is about 30 millimeters ( 1. 2 in ) long ; the German cockroach. Blattella germanica. about 15 millimeters ( 0. 59 in ) long ; the Asiatic cockroach. Blattella asahinai. besides about 15 millimeters ( 0. 59 in ) in length ; and the Oriental cockroach. Blatta orientalis. about 25 millimeters ( 0. 98 in ) . Tropical cockroaches are frequently much bigger. and nonextant cockroach relations and ‘roachoids’ such as the Carboniferous Archimylacris and the Permian Apthoroblattina were non every bit big as the biggest modern species Etymology
The name “cockroach” comes from the Spanish word for cockroach. cucaracha. transformed by English common people etymology into “cock” and “roach” . The term cucaracha ( streak bug. sp. ) originally was used for the wood louse ( the sow bug ) . but subsequently was used to intend the palmetto bug ( the winging cockroach ) . It is from this ulterior Mexican use that Americans began utilizing the term for regular ( non-flying ) cockroach. Cockroaches. like all insects. breathe through a system of tubings called windpipe. The windpipe of insects are attached to the spiracles. excepting the caput. Thus. cockroaches. like all insects. are non dependent on the oral cavity and trachea to take a breath.
The valves open when the CO2 degree in the insect rises to a high degree ; so the CO2 diffuses out of the windpipe to the outside and fresh O2 diffuses in. Unlike in craniates that depend on blood for transporting O2 and CO2. the tracheal system brings the air straight to cells. with the tracheal tubes ramifying continually like a tree until their finest divisions. tracheoles. are associated with each cell. leting gaseous O to fade out in the cytol lying across the all right cuticle liner of the tracheole. CO2 diffuses out of the cell into the tracheole.
While cockroaches do non hold lungs and therefore do non actively breathe in the craniate lung mode. in some really big species. the organic structure muscular structure may contract rhythmically to forcibly travel air out and in the spiracles ; this may be considered a signifier of external respiration.