'Knee-deep' mayflies prompt Iowa-Illinois bridge closure

SABULA, Iowa, July 24 (UPI) -- A bridge connecting Iowa to Illinois was temporarily closed when thousands of mayflies "piled knee-deep" blocked traffic, police said.

The bridge, which connects Sabula, Iowa, to Savanna, Ill., was closed Saturday night when thousands of mayflies gathered in a swarm so thick that motorcycles lost traction on the road.

There were no injuries from the minor collisions, police said.

Teena Franzen, the mother of a Sabula police officer, took video of the mayflies while riding in his patrol car Saturday night. The video was later posted to YouTube.

"I've lived in Sabula since '75, I've never seen that many before, ever," Franzen told WQAD-TV.

Sabula Police Department Reserve Officer Stephen Thayer said the mayflies were "piled knee-deep" in the roadway.

"We had Iowa [Department of Transportation] came in with a snow plow and actually plow them off and then sand it because it was still pretty slippery. And then Illinois plowed their side," Thayer said.

The Iowa DOT said the lights on the bridge will be kept off during the next few weeks to discourage the mayflies from gathering.