Citizen science meets biting pests: Determining the spatial pattern of nuisance black flies (Diptera: Simuliidae) in western Maryland

Black fly (Diptera: Simuliidae) populations were sampled in Washington and Frederick County, Maryland during the summers of 2013 and 2014 in response to complaints of biting flies from local residents. The objectives of this study were to determine the species and larval source of the adult flies, to assess the impact of the nuisance problem, and to describe the distribution patterns of the fly populations. An online survey, found at http://mdblackfly.com, was developed for residents to self report their location and the impact of the flies. Swarming adult flies were collected with an aerial net throughout the area of interest indicated by the survey results. To confirm collected flies were the same species that bothered residents, kits were given to resident volunteers to obtain fly specimens throughout the summer. These specimens were then gathered and identified to species. Larval specimens were collected from accessible streams and rivers within the area of complaint and identified to species. All of the adult black flies collected were identified as female Simulium jenningsi. S. jenningsi larvae were primarily collected from the Potomac River, indicating this as the major source of the nuisance flies. Adult fly distributions were influenced by land use and proximity to the confluence of the Shenandoah and Potomac Rivers. Differences in survey responses between the two years indicate a growing awareness about nuisance black flies and enthusiasm among residents for this research.