There are a lot of unusual phenomena happening around the world, such is the following video. A Sabula Iowa Police was called to assist a motorist on the Sabula Savanna bridge. But when the officer arrived he witnessed a terrifying scene — Millions of mayflies had hatched and made the bridge like ice.

There was a huge number of them swarming his car that he can barely see while driving.

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Even the very road surface was infested by mayflies, thereby making it dangerous and slippery!

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The Iowa Department of Transportation say that the video was taken on July 25 at the Sabula Savanna bridge over Mississippi River, where mayflies (shadflies) are swarming the area, making it to be dangerously slippery to anyone who might be passing. They are said to be in the height of their hatching season. Local law Enforcement was called to allow their DOT forces to remove the insects off the bridge.

According to Dick Banowetz, the supervisor in the area, the flies were so thick that they were actually ankle deep on the bridge!

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Once the crew removed and plowed off the bridge, they put sand for traction. One thing that attracts the Shadflies are the lights so as a precaution during hatching season the next few weeks, they will shut the lights off.

Everyone crossing the bridges are warned to be extra careful especially from the dark at night and from the road surface which might be slick again with flies soon.

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According to, Mayflies are also called shadflies and lake flies. They are aquatic insects that are attracted to light.

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They become a nuisance to people when they gather at a particular place during hatching season.

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Watch this freaking video:


H/T: Unilad

Indeed, there may have been a scientific explanation for this particular phenomena such as the flies being attracted to the lights during their hatching season. But, it indeed pays to be careful at all times.