ADDITIONAL STUDIES OF DISPERSION PATTERNS OF AMERICAN COCKROACHES FROM SEWER MANHOLES

Cockroaches in abundance are often associated with human activities and, thus, are convenient animals for ecological experiments. As a matter of general concern, cockroaches often live in association with filth and are known to carry a large number of microorganisms, some of which are pathogenic to man (Roth and Willis, 1957). That cockroaches might serve as elevator mechanisms, bring enteric disease organisms from underground sewer systems up to areas of human contact, prompted a series of experiments to determine the various factors affecting movement patterns in American cockroach (Periplanela americana [L]) populations. An initial study in Phoenix, Arizona, determined that during the summer American cockroaches had limited movements from sewer manholes under un-disturbed conditions but extensive emigration when the manhole population balance was disrupted by the super-imposition of a large number of extraneous roaches (Jackson and Maier, 1955). Movements into yards, an adjacent apart-ment, and 350 ft downstream in the sewers were recorded. The following dispersal tests were a continuation of these studies to determin