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Public Notice: Maryland Agencies to Treat Potomac River for Black Fly Control on July 11

ANNAPOLIS, MD – The Maryland Department of Agriculture—in partnership with the Department of Natural Resources—will treat a targeted area of the Potomac River in Washington County as part of a pilot program to control black fly populations in the area. Treatment is scheduled for Wednesday, July 11, starting at 8 a.m.

The department will apply a Bacillus thuringiensis israelensis (Bti)-based larvicide via helicopter (Bell 206 Long Ranger, green and white paint scheme. Tail number is N641HA). Bti is a naturally occurring bacteria found in soils worldwide. It is a bacterial insecticide, not a chemical, and is only harmful to a very limited variety of organisms including midge, black fly, and mosquito larvae and a few other aquatic Dipteran (flies) insects.

The treatment may cause temporary discoloration of the water, but it completely nontoxic and is not harmful to humans, fish, crabs or other aquatic invertebrates. More Information​

The Black Fly Suppression Pilot Program was established by the General Assembly (House Bill 508, 2016). For more information on the program, visit the department’s webpage.

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Contact Information

If you have any questions, need additional information or would like to arrange an interview, please contact:

Jason Schellhardt
Director of Communications
Telephone: 410-841-5888

Megan Guilfoyle
Public Information Officer
Telephone: 410-841-5889

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