Studies on cockroaches in a municipal sewerage system.

Summary Approximately 40 per cent of the sewer manholes in Tyler, Texas, have been found to be infested with the American roach, Periplaneta americana. Five species of roaches were taken from the sewers: Periplaneta americana, P. fuliginosa, Blatta orientalis, Parcoblatta bolliana and P. pennsylvanica. Nine species of Salmonella have been isolated from American roaches collected in the sewer manholes: S. bareilly, S. tennessee, S. newport, S. panama, S. rubislaw, S. meleagridis, S. oranienburg, S. kentucky, and S. anatum. It has been definitely determined that sewer cockroaches leave the manholes and enter homes as far as a block away. Roaches may enter homes via the sewer lines, as it has been demonstrated that under experimental conditions they will pass through the plumbing traps currently used under sinks, bathtubs, and commodes.