VIDEO: Mayfly Swarm Closes Pennsylvania Bridge, Causes 3 Motorcycle Crashes

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We had some pretty inclement weather in New England this year, but nothing like this massive mayfly swarm on the Veteran’s Memorial Bridge between Wrightsville and Columbia, Pennsylvania.

Hundreds of thousands of mayflies swarmed the Route 462 bridge Saturday evening, eventually dying and covering the road in piles inches deep, making the road surface so slick with bug guts that three motorcyclists crashed trying to cross.

Bridge Mayflies Bestride

According to Lancaster Online, Wrightsville Fire Chief Chad Livelsberger said firefighters encountered a surreal scene.

“It was like a blizzard in June, but instead of snow, it was mayflies,”  Livelsberger said. Dead mayflies about an inch thick covered a large section of the bridge.

“It was very slick, almost like ice,” the chief said. “It was hard to stop, in the engine and the vehicles. When you go to pull out, all your tires would do was spin. Visibility was zero for maybe a quarter mile (across the bridge) from the York County shore.”

According to the chief, a new type of LED lighting on the Route 462 bridge may have been attracting the mayflies. The new lights were installed a year ago as part of a $2.1 million bridge renovation project. Mayflies hatch from the Susquehanna River and gravitate toward the lights. In previous years, the bridge was lit by lights that were on tall poles much higher than the bridge’s decking. The new lights were restored to the same position they were in 1930 when the bridge was opened, about 10 feet above the road surface.

The flies mate in huge swarms and the males die immediately, falling to the ground. The females lay eggs and then also die.

Craig Fitzgerald

Craig Fitzgerald

Writer, editor, lousy guitar player, dad. Content Marketing and Publication Manager at