Flooded Mississippi River keeping mayfly numbers down - KWWL - Eastern Iowa Breaking News, Weather, Closings

Flooded Mississippi River keeping mayfly numbers down

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The hatching of mayflies is an annual -- and some say gross -- event that happens during the spring and summer months in cities all along the Mississippi River.

This year, however, Dubuque hasn't seen a single big hatch, which is very unusual.

Mayflies like to lay their eggs in and hatch out of relatively still, calm water, and with all the flooding on the Mississippi River this year, fast currents have made the water anything but calm.

Mark Wagner is education director with the National Mississippi River Museum and Aquarium in Dubuque. He said while Dubuque saw a smaller mayfly hatch earlier this year, there has not yet been a major hatch like there normally is at this point in the season.

"There are different ones that hatch at different times, so even though we're missing some of the big hatches right now, I have a feeling once the water goes down to normal levels, we'll still see a few either later hatches or some different species that do hatch," Wagner said.

Mayflies have a 24-hour life span. They hatch, breed, lay eggs and die. In past years, piles of dead mayflies have littered the streets following a hatch.

Connie Schute owns the Jewelry Box in downtown Dubuque. Like many of her fellow downtown Dubuque business owners, Schute doesn't mind the lack of mayflies. When the insects swarm the city, their leftover carcasses litter the sidewalk in front of her store.

"I bring my blower down, knowing that they're going to be here, and I blow them all out into the street and sweep them all up," Schute said. "It smells quite a bit, but once we get them swept up and blown away, they're not so bad."

As gross as the mayflies can be, Wagner said they're a sign of a healthy river, as larvae couldn't thrive in a polluted river.

"Even though we hate the mayflies when they're out and they're all over our cars and under street lights and in parking lots...if you remember it's a good sign of the river's health, then it's good to know that," Wagner said.

He said the lack of a big hatch in Dubuque likely won't have a huge impact on food supplies for fish and birds, as the mayflies are only out for about 24 hours when a hatch does happen and aren't a regular part of the animals' diet.

Mayflies are also known as fish flies.

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