ARS | Publication request: Dewatered sewage biosolids provide a productive larval habitat for stable flies and house flies (Diptera: Muscidae)

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 26, 2011
Publication Date: March 1, 2012
Citation: Doud, C.W., Taylor, D.B., Zurek, L. 2012. Dewatered sewage biosolids provide a productive larval habitat for stable flies and house flies (Diptera: Muscidae). Journal of Medical Entomology. 49(2):286-292. DOI: HTTP://DX.DOI.ORG/10.1603/ME11158.

Interpretive Summary: Waste water treatment facilities frequently store biosolids (sludge) in the open where flies can access them to lay their eggs. Biosolids are ideal substrates for the development of immature flies. In this study, we identified the species of flies developing in a biosolid storage site in eastern Kansas and estimated their population numbers. Stable flies and house flies predominated, making up 80 and 18% of the total number of flies emerging from the biosolids. Stable flies matured from May through November with emergence peaks in early July and late August. Most of the house flies emerged in July and early August. Stable flies preferred biosolids that had aged for several weeks while house flies emerged from fresher biosolids. Although the density of fly maggots in the biosolids was lower than that observed in substrates associated with livestock manure, the area of the storage site was quite large giving it the potential to be a primary source for stable flies and house flies in the area.

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