PENNSYLVANIA (WHTM) — Black flies are a common summer pest and a nuisance for those trying to enjoy the outdoors. The Pennsylvania Department of Environmental Protection takes steps to keep black flies under control.

Black flies, also known as gnats, come out with the sunshine and warm weather. “They’re the small pestering and biting gnats that swarm around your head. They aren’t the manure flies, they aren’t house flies,” said Doug Orr, environmental group manager for the DEP’s Vector Management program.

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The bugs need fast and flowing water to lay eggs and often find homes around rivers and streams. Since the Clean Water Act, enacted in the ’70s, helped clean up waterways, Orr says the flies have been expanding their territory.

The DEP is taking action to control the pests through the Black Fly Suppression Program, serving 36 counties and treating 1,700 miles of waterways. To control the flies, helicopters release an organic, photodegradable material that “doesn’t build up in the environment” and “is not a chemical,” Orr explained.

“This process continues for the entire summer. We will spray anywhere between eight to 12 times,” Orr said.

Two years ago, the department received over 7,000 complaints about black flies. Last year, the governor and legislature nearly doubled the amount of money the Black Fly Suppression Program received, and complaints dropped to less than 300.

“It means everything from farmers’ livestock being able to be out in the field without worrying about being bitten to being on a golf course to being in outdoor shopping areas, walking in downtown Harrisburg or Philadelphia,” DEP Secretary Patrick McDonnell said.