Prepare to be disgusted. Mayfly hatch underway.

As you slip on dead mayflies over the next few days, try to remember that it’s indicative of a river’s health.

The annual massive mayfly hatch on the Mississippi is finally underway, a little later than usual.

Alex Lamers, a National Weather Service meteorologist in the south, posted this radar loop, which picked up the hatch last night in La Crosse, Wisconsin.

There are millions of mayflies on buildings and roadways now, National Weather Service La Crosse meteorologist Tim Halbach tweeted.

It’s not the most fun time for filling up the gas tank:

Or grabbing some cash:

Update 3:29 pm: Or quenching a thirst:

Or doing just about anything else:

Last year, the Minnesota Department of Transportation had to call out snowplows to remove the dead mayflies from the highways.

From the archive:

  1. Listen Voices of Minnesota (1999): Dan Olson talks with Cal Fremling, Winona State University expert on the Mississippi River

  • joetron2030

    I think the fly fishers out there might be happy?

    • J F Hanson

      Or–will the fish be stuffed and not looking for fishers’ flys?

  • MrE85

    Saw some mayflies this weekend at the Coon Rapids dam. Nothing like these swarms, however.

  • Ralphy

    At least they don’t bite!

  • Veronica

    Last year? I grew up in Red Wing– They had to plow off the bridge over the Mississippi every year. It was also fun to watch them cook on the huge spotlights shining on the flag outside of Perkins. Mayflies were a brief, gross, part of life.

  • Paul Weimer

    I had dreams about these darned things last night. Gunnnh!

  • Bosda

    AAAAAAHHHHH!!!!!!!!!!!!!!!!!!!!!!

  • Bosda

    AAAAAAAHHHHH!

  • MrE85

    Yikes. I see a woman was injured in a mayfly-related accident.

  • Ross

    My dad and I use to hunt for walleyes in the middle of the night. When we would flip on the boat lights you’d swear it was snowing there would be so many mayflies.