In August, we posted a survey on our website to gauge geographical range and activity levels of black flies in Washington County. Geographical data can be seen on our map. The results of our survey indicate that 96% of respondents observed adult black flies at their place of residence. They were also observed across the county at recreational sites such as Antietam Battlefield, the C&O Canal, and South Mountain State Park. Peak black fly activity as experience by residents was between May and August, typically during conditions with little to no wind/rain, varying degrees of cloud cover, and temperatures between 70 and 80oF.
15% of respondents rated black flies a “4” on a scale 1-5, with 1 being not irritating and 5 being very irritating. The remaining 85% rated black flies a “5.” Black flies were observed swarming around the face and body and biting, with some participants commenting on severe reactions to bites. 83% respondents stated that black flies had caused them to avoid activities including gardening, picnicking, hiking, walking dogs, and sporting events. A number of respondents stated that they avoided any outdoor activities because of the presence of black flies. Some mentioned that they choose to vacation elsewhere or plan on moving away from Maryland because of this annoyance.