Swarms of mayflies made for slick road conditions Sunday night, causing a three-car crash in western Wisconsin.
Mayflies are mostly harmless – they don't bite or sting – and they only live for about 24 hours. But after mayflies hatch, they can swarm together in gray clouds that can be a real nuisance, and even an occasional danger to drivers.
Millions of mayflies swarming together can create visibility problems on roads, and make things slippery when they fall to the ground and all die in the same spot, FOX 9 reports.
That's what happened Sunday, when a mayfly-covered road caused Theresa Hunt, 24, of Ellsworth, Wisconsin, to lose control while she was driving northbound on Highway 63 around 10:30 p.m., the Pierce County sheriff's office said in a news release.
Hunt crashed into two other cars, injuring one passenger, who was taken to Mayo Hospital in nearby Red Wing, according to the release.
The Pierce County Herald reports a highway department employee responded to the scene with a plow-equipped maintenance truck to scrape and sand the slippery, mayfly-covered road.
A county official told the newspaper there were a lot of mayflies in the area Sunday night, but nowhere near as many as in July 2004 when mayflies caused a multi-vehicle accident and closed Highway 63 for several hours while the flies were plowed away.
It's currently mayfly hatching season in the Midwest. News 8000 has photos of a recent mayfly hatch in La Crosse, Wisconsin. The hatch was so thick it could be seen on weather radar maps.
Although they're bothersome to many, it's a good sign if mayflies are around. The bugs can only reproduce in areas with high-quality water – the amount of mayflies in a hatch correlates to the health of nearby lakes and rivers, FOX 9 says.