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Public Notice: Maryland Agencies to Treat Potomac River for Black Fly Control on August 20

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 to control black fly populations in the area. Treatment is scheduled for Tuesday, August 20, starting at 8:30 a.m.

The department will apply a Bacillus thuringiensis israelensis (Bti)-based larvicide via helicopter (Bell OH58, gray with blue and red paint scheme. Tail number is N659HA). 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 is completely nontoxic and is not harmful to humans, fish, crabs or other aquatic invertebrates. More Information​.

For more information on the department’s black fly program, visit our website.

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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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