Mayfly Invasion Causes Traffic Nightmare on Illinois Bridge

Thousands of mayflies have taken over a bridge in central Illinois, creating a traffic nightmare for commuters trying to make their way across the city.

The Havana Police Department warned drivers of a massive mayfly swarm on its Facebook page Monday morning, posting two photos that showed the bridge over the Illinois River and a local squad car blanketed by the bugs.

At one point the mound of insects piled 6 inches high, according to the post, making for slick and dangerous roadways for vehicles trying to make their way through the mess.

“There were already motorcycle accidents due to this and cars stuck in the center of the bridge,” police said.

Newly winged mayflies will emerge from the waters where they live until adulthood in droves when triggered by the right temperature, according to The Wall Street Journal. The insects then die within a few days.

The City of Havana Street Department and IDOT are working to get the mayflies under control, authorities said.