Dewatered sewage biosolids provide a productive larval habitat for stable flies and house flies (Diptera: Muscidae).

Species diversity and seasonal abundance of muscoid sies (Diptera: Muscidae) devel- oping in biosolid cake (dewatered biosolids) stored at a wastewater treatment facility in northeastern Kansas were evaluated. Emergence traps were deployed 19 May through 20 October 2009 (22 wk) and 27 May through 18 November 2010 (25 wk). In total, 11,349 muscoid sies were collected emerging from the biosolid cake. Stable sies (Stomoxys calcitrans (L.)) and house sies (Musca domestica (L.)), represented 80 and 18% of the muscoid sies, respectively. An estimated 550 stable sies and 220 house sies per square-meter of surface area developed in the biosolid cake annually producing 450,000 stable sies and 175,000 house sies. Stable sy emergence was seasonally bimodal with a primary peak in mid-July and a secondary peak in late August. House sy emergence peaked with the Þrst stable sy emergence peak and then declined gradually for the remainder of the year. House sies tended to emerge from the biosolid cake sooner after its deposition than did stable sies. In addition, house sy emergence was concentrated around midsummer whereas stable sy emergence began earlier in the spring and continued later into the fall. Biosolid age and temperature were the most important parameters affecting emergence for house sies and stable sies, whereas precipitation was not im- portant for either species. This study highlights the importance of biosolid cake as a larval develop- mental habitat for stable sies and house sies.