NEW ULM — If you’ve taken a drive out in the country during the morning or early evening, chances are your vehicle’s front end has a generous coating of little orange specks.

Most likely, those tiny sunbaked specks are from biting gnats, sometimes called black flies, whose population has soared within our region and much of Minnesota.

“People aren’t imagining things,” Metropolitan Mosquito Control District (MMCD) Public Affairs Coordinator Mike McLean said. “The black flies are pretty intense this year.”

McLean said the abundance of black flies this season in south central Minnesota is due to the high water levels on the Minnesota River.

He said the MMCD monitors waterways for black fly populations, and when the population reaches a target species threshold, they treat the water with a liquid bacterium that’s effective at killing flies and mosquitoes in the larval stage.

But with high water levels on the Minnesota River, he said crews haven’t been able to place monitoring or treatment buoys.

Increased precipitation during the winter and spring contributed to increased water levels on many rivers which McLean said provides plenty of breeding space for black flies.

“It has to do with the sheer volume of water in the last couple of years,” McLean said. “When you have high water there’s a lot of space for black flies to develop.”

Despite the pesky bites or increased trips to the car wash, McLean said the high population volume of the flies indicates that Minnesota’s waterways are relatively clean.

“It’s one of those ironies,” he said.

Dr. Roger Moon, a professor of entomology at University of Minnesota Twin Cities, said black flies require clean, flowing waterways to properly breed and sustain their population.

He said clean water is vital for a black fly’s life cycle that begins with biting a victim, and ends when they return to a waterway to lay eggs.

Two to four days after being laid, black fly larvae eggs hatch in flowing streams and rivers where they begin to feed on particles in the water. The tiny larvae capture these particles with specially adapted “raker gills” that resemble yard rakes, Moon said.

After a development stage of 10 days to several months — depending on water temperature or species — the larvae enter the pupal stage where they begin to mature into adults. The adult emerges from its pupal case after riding a bubble of air to the surface where they then find a fellow adult to mate with.

“They fly away from those sites to find hosts to feed on,” Moon said.

Like mosquitoes, the female black flies seek out a blood meal to ensure the full development of their eggs.

Moon said black flies have “stilletto-like” proboscises that they use to slash and probe into the skin of a victim. From there, the flies secrete saliva containing an anticoagulant that helps the blood flow more easily. Moon said the flies’ saliva is the cause of the itchiness and painful swelling characterized by the bite.

A black fly bite often leaves a small puncture wound that may result in anything from slight swelling to a swollen bump the size of a golf ball. The symptoms, including itchiness, may last anywhere from a few days to a whole week.

“It depends upon the fly and the sensitivity of the victim,” Moon said.

According to the Metropolitan Mosquito Control District, black flies are not known to transmit diseases to humans.

Moon said black flies will not travel indoors or bite victims at night, and the best way to avoid bites is to use bug repellants containing high DEET concentrations.

Gage Cureton can be emailed at gcureton@nujournal.com.