As a life long resident of Peoria, Illinois, I spent many a summer on the river. But, one thing I hated the most was dealing with Mayflies. 

De Agostini/Getty Images

A Mayfly is an insect that is harmless to humans. They are very important to the ecosystem of rivers, especially the Mississippi and Illinois Rivers. Every year, they hatch and let me tell you, there are thousands and thousands of them. They all travel together.

You won't find these flying insects around your house, unless you live close to a river. A town that is close to where I used to live is Havana, Illinois. It is located along the Illinois River. A couple of days ago, the Havana Police Department warned residents to slow down over a bridge that crosses the river. Thousand of these mayflies covered the bridge and caused the road to be slick.

Havana Police Department via Facebook

Another cool thing that tells you mayflies are here is a weather radar. Here is a link to an image of mayflies ascending to the Mississippi River in La Crosse, Wisconsin. No, that  is not rain, those are mayflies.

If you are interested in this neat phenomenon, click on this link to find out more.