Brace yourselves: Michigan’s annual swarm of mayflies is nearly here.
The short-lived, yet creepy, annoying and sometimes overwhelming insects will emerge from lakes and streams within the next few weeks as water temperatures warm.
Mayflies, aquatic insects also known as fishflies, emerge from streams, rivers, ponds and lakes in Michigan around mid- to late June, most notably from Lake Erie and Lake St. Clair, according the Great Lakes research program Michigan Sea Grant.
Each year, their emergence depends on the water temperature. Typically, once waters hit 68 degrees they become active — and they are hard to miss when they do.
Adult mayflies gather in large groups with one mission — reproduce, then quickly die with a 5-minute to two-day lifespan.
“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.
With temperatures gradually warming, it may be helpful to prepare your house or yard for the fluttering swarms of these fleeting insects.
More on Michigan’s Mayflies:
What do mayflies look like? How long do they live?
Mayflies are small (quarter-sized or larger) aquatic insects. They spend most of their life cycle in water, then once they reach adulthood they leave to mate, according to the National Wildlife Federation.
There are more than 600 different mayfly species in the U.S., with more than 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. Their upward wing posture is a key way to identify them.
Adult mayflies don’t develop functional mouths, so don’t even feed during their brief lifespan, MSU Extension says, and they don’t bite or sting.
Adult male mayflies can live for one to two days after they emerge from water, according to the International Fund for Animal Welfare. Adult female mayflies are said to only live for a as little as five minutes.
“Ecologically, mayflies matter more than their short lives might suggest. They’re a primary food source for fish, birds, and bats. Plus, scientists use their populations as a water quality indicator. A large, healthy emergence near a local waterway is generally a sign that the water is in good shape,” the Michigan and Ohio based pest company NexGreen said.
When will mayflies emerge in 2026?
Each year, their emergence depends on the water temperature. Typically, once waters hit 68 degrees they become active — and they are hard to miss when they do.
Current Lake Erie temperatures suggest the swam could be days away.
The temperature off Gibralter, near the mouth of the Detroit River, was 62 degrees on May 28.
The water temperature near Stony Point, Toledo and Monroe was 61 degrees on May 28. At Luna Pier, the temperature was 62 degrees.
Can I keep mayflies away?
Nothing will stop mayflies from swarming, but as warmer summer air moves in, you can discourage mayflies before they arrive in swarms at your home, according to NexGreen:
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 and mayflies have a more upright wing posture, according to NexGreen.
Contact Sarah Moore @ smoore@lsj.com
This article originally appeared on Lansing State Journal: Michigan is home to creepy flying insects. And they’re about to swarm
Reporting by Sarah Moore, USA TODAY NETWORK / Lansing State Journal
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