A massive swarm of mayflies, detected by National Weather Service weather radar starting after 9 p.m. Thursday, invaded downtown Burlington, Iowa along the Mississippi River.
Piles of flies were inches deep in spots.

The insect swarms are coming up the Mississippi, towards the Twin Cities.
Right now, areas south of the Twin Cities metro are dealing with bug problems after a massive swarm of mayflies hatched from the Mississippi River.
The mayflies also made an impact on WCCO’s weather radar:
In Hastings, residents are also reporting problems with the bugs. In response, city officials have decided to shut off street and parking lot lights in the downtown area, as well as along the bridge and riverfront, starting Thursday night through the weekend.
Parts of the south metro are dealing with bug problems recently after a massive swarm of mayflies hatched from the Mississippi River.
Thursday, things were quiet in Hastings but remnants left behind, including large piles of flies, were evidence of a very active night.
Looks like the start of a mayfly hatch on the Mississippi as of 9:40 pm, especially near and south of La Crosse. Anyone have reports/photos? pic.twitter.com/NxxkPmVHTL
— NWS La Crosse (@NWSLaCrosse) July 6, 2017
“I got closer and closer and all of a sudden I was like ‘oh my gosh, that is not dirt’ and I just saw all these bugs and the ones in the pile they’re all clumped up in these huge hills,” said Andrea Egan.
It’s what happens this time of year along the river mayflies hatching, reproducing, laying eggs and then dying – all in about a day.
“I am usually not scared of bugs but I’m like nope, not when they outnumber me,” she said.
TW// bugs
— kayla ✧ (@serimdoll) July 3, 2020
my town is right next to the mississippi river and we currently are having a mayfly hatching and they are swarming our downtown area ?? pic.twitter.com/iH9Iz6hO1P
The City of Hastings is used to what happens here each year and they try to get ahead of the swarm.
“What we do is a proactive step is we turn all the lights off when we have the first inclination of this hatch coming and that does a lot to mitigate or lessen the attraction,” said Hastings Director of Public Works Nick Egger.
But some years are worse than others
“As recently as 2016 we did have to get out our shovels and snowblowers and street sweepers to pick up some pretty large piles and accumulations of them,” said Eggers.
So far, it hasn’t been that bad but Wednesday night’s hatch could be just the start.
And the invasion seems worse in Canada:
“Sometimes it’s been one larger hatch,” Eggers added. “Sometimes it’s been two or three moderate ones. It’s really been all over the board.“
While the insects may not be popular, it’s actually a sign of a healthy river as mayflies are found when the freshwater systems have good oxygen levels. Please close your mouth when walking or training outside… Happy fishing!
More insect swarm invasions on Strange Sounds and Steve Quayle. Now if you are looking for supplements to increase your healthy lifestyle and sexlife please visit Natural Health Source. Thank you for your support! [Fox 9, BMN, CBS Local Minnesota]