Blatella asahinai is a pest species that was introduced into Florida during the late 20th Century and has since spread to neighboring states and across the southern US. In the field, adult Blatella asahinai can be readily distinguished from the German cockroach: Blatella asahinai flies, the German cockroach does not. Immatures, which are often the most numerous individuals require chemical or molecular markers to reliably identify to species. Before DNA barcoding and other DNA-based techniques had been developed, Carlson and Brenner* developed method to use cuticular hydrocarbon differences to distinguish species of Blatella. This method of ID was the best in its day, but chemical methods have been widely replaced by DNA methods that are more rapid and less expensive than chemical methods.
D. A. CARLSON AND R. J. BRENNER. 1988. Hydrocarbon-Based Discrimination of Three North American Blattella Cockroach Species (Orthoptera: Blattellidae) Using Gas Chromatography. Ann. Entomol. Soc. Am. 81(5): 711-723.