Skip to main content

That's not rain on the radar – it's bugs


No that wasn't rain on the weather radar.

The National Weather Service in La Crosse tweeted a radar loop from 9:40 p.m. Wednesday night, showing what appears to be one of the first mayfly hatches of the season along the Mississippi River in southern Minnesota.

That's right. There were so many mayflies it could be seen on the radar.

This is a pretty common occurrence along the river this time of year, according to the National Weather Service in La Crosse, which tracks mayfly hatches. 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.

Some years the hatches are bigger than others. 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 pretty gross, but an abundance of these harmless insects is a good thing. Mayflies only hatch from waterways with high-quality water, the Minnesota DNR's website says.

So at least we know the river is clean, right?

And if you're not grossed out yet, check out this video of a bunch of dead mayflies outside of a Dunkin' Donuts in Prairie du Chien, Wisconsin, early Thursday morning.

Here are some more mayfly photos:

Posted by Jim Little on Thursday, July 6, 2017

Next Up

Maple grove fire

5 youths are 'persons of interest' in Maple Grove greenhouse fire

Police say it's being investigated as a possible arson.

Dave Hutchinson

Dave Hutchinson has police license suspended for 30 days

The sheriff's suspension will begin on Nov. 22.

minnesota bureau of criminal apprehension - bca

Man with sword, officers who shot him in North Branch identified

The 31-year-old was shot multiple times in the Friday incident.

Jeff Plush

MN-based USA Curling 'reviewing' report that CEO ignored abuse in NWSL

Jeff Plush is under fire for multiple allegations made by U.S. women soccer players.

Axdahl's Garden Farm & Greenhouse

7 Minnesota pumpkin patches to visit this fall

Plenty of patches to pick the best pumpkin

slushy snow

Sven Sundgaard responds to AccuWeather's winter forecast

Take anything beyond a couple weeks with a grain of salt, warns meteorologist Sven Sundgaard.


Rage Against the Machine cancels rest of tour, including MN shows

The cancellations include a 2023 stop at the Target Center.

Screen Shot 2022-10-04 at 11.03.16 AM

Watch: Speeding drivers use Minneapolis bike lanes to overtake

Community members have called for better safety precautions in response.


See the piles in the picture? They're dead bugs

We know mayflies are a sign of a clean river. But still, ew...

See the piles in the picture? They're dead bugs

We know mayflies are a sign of a clean river. But still, ew...

Screen Shot 2019-06-11 at 7.18.33 AM

That's not rain on Duluth's weather radar – it's birds

Meteorologists in Duluth were curious what the blue blob on radar was.

That's not a storm on the radar, it's geese

Migration season has arrived in the midwest.