You’re Not Seeing Mayflies Around Town – Those Are Midges

As I jumped on my bike and left the Lowell Elementary playground after dropping my kids off yesterday morning, I overheard a conversation between two parents that I hear pretty consistently this time of year. It went something like this:
Parent 1: “Ugh, can you believe these swarms of bugs?”
Parent 2: “Yeah, those are the mayflies. They’re always bad in the spring.”

The mayfly is NOT the same thing as a midge. Photo: Minnesota Pollution Control Agency

If by, “bad,” Parent 2 means “astonishingly abundant,” then yes, May is peak “badness.” But those clouds of little flying buzzing bugs are not mayflies. In fact, if you wanted to argue about “badness,” mayflies are impressive swarmers in their own right – showing up on radar and causing traffic problems in spots in cities across the U.S. nearly every year.
Midges are more on the “pesky” side of bug annoyance. Although they resemble mosquitoes, they don’t bite. But they sure are drawn to light and will absolutely cover your siding or windows if you have one on at night.
This is a midge. Photo courtesy

What we’re seeing (or swatting at) in Wisconsin right now is the midge in its adult form. Before they emerge to cloud our skies, they are little worm-like larvae living in shallow freshwater habitat, where they eat decaying plant matter and are, in turn, a big food source for a lot of fishes.
Once those larvae complete their life-cycle and emerge as flying adults, they stop eating and have only one thing on their minds – mating. So they gather in huge clouds and, well, get to to know one another. After mating, the male eventually expires, with the female not far behind – first she’ll return to the water to lay her eggs.
While our annual midge season in Wisconsin sure can be pesky, just be thankful that you don’t live along the shores of Lake Myvatn in Iceland, which is home to Biblical plague-level swarms of midges. In fact, researchers at the UW-Madison have been studying Myvatn’s midges over the last several years and, well, the picture below pretty much sums up what those field experiences can be like!
Okay, that’s “bad.”

One of the coolest phenomena (at least in my opinion!) is how midges collect on the downwind side of structures (like trees) and form columns that look almost like smoke blowing in the wind. Last year there were so many of these columns (and they were so large) that, during a few particularly still, warm evenings, my neighborhood was awash in a low-level ambient hum. The video below doesn’t really do this justice, but you get the idea!

Anyway, now you know – mayflies and midges are both prone to epic swarms, but they’re not the same thing. And if you’re anywhere near a lake in Wisconsin (or across much of the U.S.) at this very moment, you can now turn to a colleague or fellow parent at drop off and say “Wow, the midges are really good this year.”