DUBUQUE (KWWL) -
The largest emergence of mayflies in Dubuque this year left the city's streets littered with the insects' carcasses Sunday morning.
Mayflies -- or fish flies, as some call them -- are winged insects that don't bite or sting. They live most of their lives as larvae in the river and emerge, like they did Saturday night, for just 24 hours to mate, lay eggs and die.
Cheryl Callahan owns Callahan Photography in downtown Dubuque. Sunday afternoon, she was outside her shop, sweeping up the dead insects.
"There's thousands of them. They basically come in and they take over our downtown area," Callahan said. "Anybody who has lights, they shut them off. Even on the bridge, we shut out the lights. The other thing is, if you're driving, if you get too many of them underneath your car, you can actually slide on them. They're slippery."
Mark Wagner is the education director at the National Mississippi River Museum and Aquarium in Dubuque.
"Lights draw in the mayflies or ephemeroptera," which is the insect's scientific name, Wagner said earlier this month. "The more powerful the light, the more you're going to have."
There are usually two or three mayfly emergences in Dubuque throughout the summer. Saturday night's was the second and biggest in Dubuque this year. However, Wagner said a big mayfly emergence is a sign of a healthy river.
"In a polluted system, polluted waterways, they die, they can't live, so I guess look at the bright side and say that, 'yeah, maybe these insects bother me, but because they're here, that means that the river right outside our backdoor is in pretty good health,'" Wagner said.
A downtown Dubuque business owner sweeps dead mayflies into a dustpan Sunday afternoon
