Pest Organisms / Oriental Cockroach
Signs
The clearest evidence shows up in the damp zones they prefer. Inspecting crawl spaces, basements, and kitchen and bathroom plumbing can turn up dead roaches, egg cases, and dark fecal smears. Source: https://ask.ifas.ufl.edu/publication/IN316
Roaches streaming up out of floor drains, or clustered near leaks and standing water, are another strong sign. Source: https://extension.usu.edu/planthealth/ipm/notes_nuisance/oriental-cockroach