The first big mayfly hatch of the season happened in the Upper Mississippi River Valley and was significant enough to visualize on weather radar.
A map from the National Weather Service showed the swarms overtaking parts of the map. The mayflies flew as high as 2,500 feet above ground near La Crosse, Wisconsin, according to the Huffington Post.
The mayflies surrounded gas pumps, ATMs, vending machines and lights and made them inaccessible, according to KARE 11, a Minnesota outlet, and photos posted by the NOAA.
The bugs also turned surfaces, of everything they landed on, slimy. Roads even became mayfly-coated and caused a three-vehicle crash in Trenton, Wisconsin.
This mayfly hatch was a larger black-brown Bilineata species that emerge from river mud during the warm season, according to the National Weather Service.
The mayflies have a lifespan of a few hours to a few days and once they die they become another problem.
Once the bugs die, they pile up in front of doors and machines. Some places even had to use snowplows to begin cleaning up the mess.