The cockroach, contrary to popular belief, isn’t one species. There are over 4600 varieties of cockroaches, of which 30 are considered pests—largely due to their unintended “domestication” by thriving in human environments., where different species evolve similar traits independently, often as a response to similar environmental pressures. This evolutionary mechanism has enabled cockroaches to colonize a range of ecological niches around the world.
Genomic research has mapped out two major pathways for the global spread of German cockroaches: an older route that took them westward to the Middle East around 1,200 years ago and a more recent eastward expansion during the European colonial era about 390 years ago. The eastward expansion, occurring approximately 390 years ago, was likely driven by the European colonial powers’ commercial activities, particularly those of the Dutch and British East India Companies. These companies established extensive maritime trade networks between South and Southeast Asia, providing ideal conditions for the transportation and establishment of German cockroaches in new regions.
The current genetic makeup of German cockroach populations reflects the political boundaries of countries today. This pattern suggests that as international trade expanded, different regional populations of German cockroaches were established.