Mayfly hatch overwhelms upper Midwest
On the evening of July 20, 2014 mayflies hatched along along the Mississippi river between Minnesota and Wisconsin in such great numbers that they were picked up by radar resembling light rain. the hatch began around 8:35pm. According to the National Weather Service: "this particular emergence was that of the larger black/brown Bilineata species. The radar loop below shows the reflected radar energy (reflectivity) from 8:35 pm to just after midnight. The higher the values (greens to yellows) indicate greater concentrations of flies. Note how the swarm is carried northward over time."
Mayflies swarm Mississippi river
A gas station is enveloped in Minnesota.
Mayflies swarm Mississippi river
The lights of the gas station canopy hint at their numbers.
Mayflies swarm Mississippi river
A gas pump is covered
Mayflies swarm Mississippi river
Mayfly nymphs cover an ATM.
Mayflies swarm Mississippi river
Mayflies hatch as a group and live for a few hours to a few days.
Mayflies swarm Mississippi river
The St. Paul Pioneer press reports that the hours-old insects may be to blame for a three-car accident in Trenton, Wisc. In some years snowplows have been used to clear the mayflies from roads.