Why No-See-Ums Are Now Feasting On People In Minnesota

Anyone who spends any time outdoors in Minnesota has likely heard about, and even experienced, what everyone I know calls "no-see-ums."

Those are the tiny little pests who seem to quietly feast on people, who are often unaware until later on or the next day, when countless itchy little bites show up.

This happens all the time at our cabin, which is south of the Twin Ports area, and where we often spend hours around the fire with family and friends talking and telling bad jokes, all while listening to music or nature.

There have been several occasions when we comment on how the mosquitoes aren't bad, only to wake up the next day covered in annoying bites that weren't from mosquitoes, but from annoying no-see-ums.

I expect that at my cabin, but over the past couple of weeks, they've been messing with me while I'm out on a run. I run several times a week, and lately, when I've been out in the early evening to avoid the heat, I've come home with a lot of dead no-see-ums stuck to my sweaty shirt and, of course, itchy bites soon thereafter.

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This is a new experience, so I decided to dig a little deeper into these pests to find out what they really are and what we can do about them.

What  Exactly Are No-See-Ums?

Despite the folksy name, no-see-ums are a very real insect — tiny biting flies in the family Ceratopogonidae, and the ones doing the damage around here belong to a group called Culicoides.

You'll also hear them called biting midges, punkies or gnats. They measure just one to three millimeters, which is the whole problem: they're small enough to walk right through a standard window or porch screen, so keeping them out takes special fine "no-see-um mesh."

You can find them throughout Minnesota, and the state's landscape is practically built for them. Their larvae develop in moist ground — the edges of marshes, bogs, ponds, streams, and plain old saturated soil — and a state this full of lakes and wetlands offers them endless nurseries.

They run through multiple generations over a summer, and a late-season batch tends to peak in that warm, humid stretch of late August into September.

Conditions matter as much as the calendar. Culicoides midges typically wait until dusk to feed, with a second wave around dawn, and they love calm, sticky, windless air.

Because they're weak flyers, even a light breeze grounds them — which is why a still evening by the water is when they're at their worst. And they'll keep at it right up until the first hard frost finally shuts them down.

Do All No-See-Ums Bite?

The truth is that only the females bite, because they need a blood meal to produce eggs. The males spend their lives peacefully sipping nectar. So every welt you're counting came from a female looking to reproduce at your expense.

They track us down largely by the carbon dioxide we exhale, along with body heat and moisture — which, if you're a runner like me, is basically a wanted poster.

And for a bug you can barely see, the bite is shockingly brutal. A no-see-um doesn't politely tap you the way a mosquito does — the female comes armed with four tiny cutting blades and a set of scissor-like jaws she uses to saw the skin open.

Then it gets even less polite: she spits an anticoagulant into the wound so your blood won't clot, and laps up the little pool that wells up — one naturalist compared it to a miniature blender turning you into a smoothie.

You usually don't feel that first slice at all. It's the proteins in her saliva that rat you out hours later, when your skin fires back with those maddening, oversized welts that itch for days. All of that from something the size of a pepper flake.

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A sweaty shirt on a warm, still evening is exactly the beacon they're hunting for, and while plenty of them meet their end stuck to that shirt, they clearly consider the sweaty run a worthwhile gamble.

What You Can Do To Fight Back

Unfortunately, there's no silver bullet to get rid of these little turds, but there are real ways to tip the odds a little in our favor.

Your best two levers are timing and wind. Since these midges peak at dusk and dawn and can't fly in a breeze, shifting outdoor time to the brighter, breezier part of the day — or picking a more open, exposed route over a shaded, low, damp one — makes a genuine difference.

Repellents help, but manage your expectations. Entomologists note DEET is only marginally effective against no-see-ums, and lab studies have found oil of lemon eucalyptus can work about as well.

Covering up with lighter-colored clothing cuts down bites too, and for the cabin, swapping standard screens for tight no-see-um mesh is the one thing that reliably keeps them outside where they belong.

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Beyond that, patience is the real cure. These little vampires are creatures of warm, moist, frost-free weather, and up north, that window is closing fast. The first hard freeze will wipe the slate clean — and after a week of picking dead ones off my shirt and itching like crazy, I can't say I'll miss them. R.I.P.