Adult mayflies — sometimes called fishflies — will soon emerge Michigan’s Great Lakes, streams and rivers for their final act: reproduce in giant, fluttering swarms and, well, dying.
“The mayfly crams its adulthood into a brief period. Within 48 hours, they develop wings, fly toward land, mate and die. If you reside near one of the Great Lakes, your garden or home and community may briefly be overwhelmed with up to 88 billion mayflies,” according to Michigan State University’s Extension.
Once they emerge from water, adult male mayflies can live for one to two days, according to the International Fund for Animal Welfare.
Female mayflies are said to only live for a mere five minutes.
“Although there are several species among many groups of insects that exist for only a few days as adults, the shortest adult reproductive life belongs to the female of the mayfly Dolania americana (Ephemeroptera) which lives for less than five minutes after its final molt,” according to the University of Florida’s Book of Insect Records.
Mayflies typically emerge from their water source around the start of summer, typically in June.
Here’s what to know about Mayflies in Michigan:
What is a mayfly?
Mayflies are small (quarter-sized or larger) aquatic insects. They spend most of their life cycle in water then, as adults, they leave to mate, according to the National Wildlife Federation.
There are more than 600 different mayfly species in the U.S., with over 100 in Michigan.
Mayflies have four translucent wings (similar to a dragonfly), large eyes, a long segmented abdomen, two or three prominent tails, six legs and two antennae.
Adult mayflies don’t develop functional mouths, so don’t even feed during their brief lifespan, MSU Extension says.
When will I see mayflies in Michigan 2025?
Around mid- to late June, mayflies emerge from streams, rivers, ponds and lakes across Michigan, according to Sea Grant Michigan, a Great Lakes research program. The timing is based on temperature, and typically the insects emerge when the water temperature reaches 68 degrees Fahrenheit.
You can monitor water temperatures in the Great Lakes online.
What’s the difference between a mayfly and a midge?
Mayflies and midges are look-a-likes due to their shared stringy, flappy and aquatic nature. To make the distinction, midges are often smaller, according to the Northeast Ohio Regional Sewer District.
What do mayflies eat?
Adult mayflies do not eat, hence their quick death. Nymphs eat detritus, other plant material and some insects, the NWF said.
Are mayflies dangerous?
No, mayflies are not considered dangerous. They can’t bite or sting, according to Birds&Blooms.
Seeing mayflies is a sign of a healthy environment, because they lay eggs in clean water.
“Mayflies are highly sensitive to pollution and other changes in their environment,” Stroud Water Research Center said. “When they are missing or few in number, it is a warning that a stream isn’t healthy enough for mayflies to live there.”
How can I keep mayflies away from my house?
While they are not harmful, they can be annoying to waterfront community residents.
If you want to keep mayflies away, here are some tips from pestworld.org:
Outdoor lighting often attracts bugs because they are drawn to the light’s UV output, according to Dodson Pest Control.
“Insects generally see three colors of light, ultraviolet (UV), blue and green. Bright white or bluish lights (mercury vapor, white incandescent and white florescent) are the most attractive to insects,” the pest company said, “Yellowish, pinkish, or orange (sodium vapor, halogen, dichroic yellow) are the least attractive to most insects.”
Is anyone actually happy to see the bugs?
Well, besides birds and fish, which will gorge themselves on the insects, the city of Dundee hosts an annual festival.
The 24th annual Mayfly Music Festival is set for June 20-21, 2025, at Wolverine Park along the River Raisin in downtown Dundee.
Contact Sarah Moore @ smoore@lsj.com
This article originally appeared on Lansing State Journal: Billions of these insects are ready to pounce on Michigan. When mayflies will emerge
Reporting by Sarah Moore, Lansing State Journal / Lansing State Journal
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