April 18, 2022 Baltimore County

Towson, MD—County Executive Johnny Olszewski today announced a joint effort with the Maryland Department of Agriculture to reduce the nuisance midge population on Back River. From early April through the fall of 2022, the Baltimore County Department of Environmental Protection and Sustainability (DEPS) will conduct aerial midge suppression treatments on a 1200-acre section of upper Back River.
“We are committed to ensuring those who visit, live and work along Baltimore County’s waterways are able to enjoy our amazing outdoor activities,” said Baltimore County Executive Johnny Olszewski. “We are grateful for our partnership with Secretary Bartenfelder and the Department of Agriculture, in which we are establishing a long-term solution for suppressing this challenge in a safe and efficient manner.”
The County and state will split the $825,000 annual cost to apply a non-toxic Bti-based larvacide from a helicopter five to six times this spring and summer with the goal of reducing the midge population to tolerable levels.
"Midges have been a consistent nuisance to the many communities along the Back River,” said Maryland Department of Agriculture Secretary Joe Bartenfelder. “I am glad to see the county's program move forward and provide some much-needed relief to local residents and businesses."
Safe and Effective Non-Toxic Treatment Targets Midge Larvae
Bti (Bacillus thuringiensis israelensis) is a naturally occurring bacteria that is found in soil, and is only harmful to certain organisms, specifically midge, black fly and mosquito larvae and a few other aquatic flies. Research shows that it does not harm people, fish, crabs or other aquatic invertebrates. It specifically targets midge larvae at particular times in their life cycles.
Trained, certified technicians from the County’s contractor, Helicopter Applicators Inc., following all applicable regulations and industry best practices, will spray a Bti-based naturally-occurring bacterial larvacide from a low-flying helicopter, during daylight hours, actively avoiding boaters and human activity in and around the water. More information about Bti is available on the Maryland Department of Agriculture (MDA) website.
Midges are small non-biting aquatic flies that often swarm near water or marshy areas where they breed. In recent years, people have observed an increased prevalence of these swarming insects, which create a significant nuisance for homeowners, boaters, businesses and recreational activities.
“I am pleased that the county and state were able to partner on this serious quality of life and economic issue. I think the partnership is an example of how differences can be set aside for the betterment of our constituents. After years of advocacy from me, citizen leaders like Sam Weaver and Karen Wynn, and scientific research and testing by Baltimore County the helicopter treatments have been a long time coming. I thank all those involved in making it happen.”
Multiple Helicopter Applications of Upper Back River this Spring and Summer
Treatment began on April 11, and will continue every four to five weeks until fall. These timeframes are estimates and will be scheduled depending on need, as indicated by DEPS’ biological monitoring of the midge larvae abundance. Each application is expected to take one to two days, with the timing dependent on wind and weather conditions and tidal movement.
DEPS will treat a 1200-acre open water area of upper Back River from Walnut Point northwest to Powell’s Point and the I-695 crossing, including portions of Deep Creek, Duck Creek, and Bread and Cheese Creek.