Yes, we know a large mayfly hatching signifies a healthy Mississippi River, but you can't look at the above picture and tell us you don't feel a little queasy.
That was the scene at Lock and Dam 3 in Welch, Minnesota, where the U.S. Army Corps. of Engineers has been sweeping up dead mayflies that have been piling up on the banks of the Mississippi.
We reported last week how the hatching of mayflies along the river had been so big this year that it could be seen via weather satellite, and it looks like riverside locations are bearing the brunt of a mayfly invasion.
According to the National Weather Service in La Crosse, a few times a year, the bugs emerge from the river as adults, find a mate, drop their eggs back into the water, and then die soon after.
The result is what you seen in these pictures posted on Facebook by the Army Corps.
The NWS tracks mayflies during the season and reported that on Tuesday there was a "major emergence" near La Crosse, Wisconsin, which then spread north.
This follows "relatively light mayfly activity" during the summer so far, and on Tuesday it saw La Crosse have to deal with a thick swarm.
The last “massive emergence” of mayflies was on July 20, 2014, when there were so many mayflies flying around it made it hard to see.
And if they all die in the same place, their dead bodies can make roads slippery. In fact, the dead bugs caused a driver to lose control and crash in Wisconsin that year. In other years, snowplows have been called in to clear the dead bugs off the road.
The crazy amounts of bugs covering everything in your neighborhood can be quite a gross sight, but as we said at the top of the page, the abundance of these harmless insects is a good thing. Mayflies only hatch from waterways with high-quality water, the Minnesota DNR’s website says.