Authorities say the swarm was so dense it caused motorcycle crashes and dead insects formed a pile several inches high

This article is more than 5 years old

This article is more than 5 years old

A swarm of mayflies was so dense it caused motorcycle crashes and prompted the closure of a bridge in Pennsylvania, police said.

The LNP newspaper reported that mayflies swarmed around the lights on the bridge and then fell to the ground, forming piles several inches deep on the road.

Police in West Hempfield township in Lancaster County said the bridge between Columbia and Wrightsville was shut down at about 10:30pm on Saturday.

Chad Livelsberger, chief of the Wrightsville Fire Company, said three motorcycle crashes occurred because of the flies. Details on any injuries were not immediately available.

Officer Brad Rohrbaugh said the bridge was reopened sometime before 6am Sunday.