Authorities say a Pennsylvania bridge has been closed for a second straight night because of swarms of mayflies so thick that they caused accidents. Wrightsville fire officials say the Route 462 bridge over the Susquehanna (suhs-kwuh-HAN'-uh) River between Columbia and Wrightsville was closed Sunday night. Chief Chad Livelsberger says a vehicle slowing because of the insects caused a crash, though he doesn't believe anyone was seriously hurt. The bridge was also closed Saturday night after three motorcycle crashes attributed to the flies. Livelsberger says the department was dispatched to deal with one crash and saw two more crashes while on the scene.
Mayflies are attracted by light and congregate on roads, bridges and other surfaces. When cars hit them, the females' eggs release liquid that makes roads slick.
Livelsberger said motorists driving through a mayfly swarm should treat it like an actual blizzard, expecting zero visibility and remains creating a slick coating on the ground. "If they're going through something like that, err on the side of caution," he said. Lt. Sean Montgomery of the Columbia Borough Fire Department compared driving on the bug-covered surface to driving on ice or snow - but he said the winter scenario doesn't include the horrendous smell, "like dead fish." Tom Smith of the Penn State Extension in York County said despite the hazards and annoyance that the swarms are causing, it's actually a good thing in the broad scheme of things.
Mayflies are relatively primitive insects and exhibit a number of ancestral traits that were probably present in the first flying insects, such as long tails and wings that do not fold flat over the abdomen. They are aquatic insects whose immature stage lives in fresh water. They are unique among insects in having a fully winged terrestrial adult stage, the subimago, that moults into a sexually mature adult.
