Things To Do In The Upper Peninsula
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Bug Off! ULTIMATE Guide to Black Flies in Michigan’s U.P.

Anyone who lives in or has roamed the Upper Peninsula can tell you that black flies are a nuisance to be reckoned with. The black flies in Michigan’s Upper Peninsula tend to attack in large swarms and like to bite around the ears and face — leaving you swollen and itchy in the worst areas possible!

With more than 65 black fly species in Michigan — mostly in the northern regions — we get a lot of questions about them. So, we’ve put together this guide to everything you need to know about black flies in the Upper Peninsula, as well as info about other biting insects to watch out for.

Things To Do In The Upper Peninsula

Quick FAQs About Black Flies in Michigan’s Upper Peninsula

Are there black flies in the Upper Peninsula of Michigan?

Yes, it’s widely known that black flies are prevalent in the Upper Peninsula of Michigan, particularly in the western part of the region and along the Lake Superior shoreline.

What time of year are black flies most active in the Upper Peninsula?

Black flies are most active in Michigan’s Upper Peninsula between dawn and dusk from mid-May to mid-July.

How do you keep black flies off you?

You can keep black flies off you while exploring the Upper Peninsula by keeping your skin covered with long, tucked-in clothing and a bug hat with netting.

Since these flying insects are attracted to dark colors, light-colored clothing is the most ideal.

Can black flies bite through clothing?

No, black flies in Michigan’s Upper Peninsula are unable to bite through clothing.

What is the best repellent for black flies in Michigan?

The best repellent for Michigan black flies is one that contains DEET, and Wondercide is a popular brand. You can also use natural repellents, such as lavender and pine oils and vanilla extract.

Want to know more? Keep reading…

Brockway Mountain Drive - Keweenaw Peninsula, Michigan
Brockway Mountain Drive

Overview of the Upper Peninsula’s Black Flies

Also known as buffalo or turkey gnats, black flies are small, robust flies and one of the most annoying biting flies for people, poultry, livestock, and other wildlife. They are attracted to the CO₂ that we and these animals exhale.

There are only six species in Eastern North America that are known to bite humans, though. The other non-biting species are irritating because they like to fly around your head and could crawl into your mouth, nose, eyes, or ears — ew!

NOTE: Although U.S. black flies don’t transmit diseases to humans like in other regions of the world, bites around the eyes can cause black-fly fever as the result of an infection, but this isn’t very common. Also, swallowing a non-biting black fly can cause symptomatic toxic shock, but this is rare.


Since there are dozens of black fly species, this insect ranges in size from 5 mm to 15 mm. They generally have robust, arched bodies with short antennae, large compound eyes, and fan-shaped wings. And while most species have black bodies, some are orange or yellow.

Feeding Habits

Like mosquitoes, female black flies are the only ones that feed on the blood of any warm creatures they can find — mostly mammals but also birds. They require blood for egg fertilization.

The unfortunate thing is that about 90% of black flies are female. For the most part, black fly females feed during the day and prefer to target the head and upper body.

FACT: The mouths of male black flies aren’t designed for biting, and they aren’t attracted to humans. Instead, males feed on nectar.

Porcupine Mountains Cropped
Lake Of The Clouds | photo via _sovereign_photography_

Where & When Michigan Black Flies Are Most Prevalent in the Upper Peninsula

While black flies can be found across the country, you can see black flies in Michigan’s Upper Peninsula as early as late April and as late as early September. Black fly season is so long because of the number of species. The peak season, though, is from mid-May to mid-July.

Black flies tend to emerge in the Western Upper Peninsula and along the Lake Superior shoreline before anywhere else. Because of that, they can get particularly “swarmy” in many of the region’s top destinations — such as the Porcupine Mountains Wilderness State Park or Pictured Rocks National Lakeshore.

When it comes to the time of day, black flies tend to emerge during dawn, and their activity only increases as the day goes on before slowing down at dusk. Black flies prefer moderate temps, moisture, and calm winds too, so you won’t see as many on hot, dry, and windy days.

Breeding Habits & Development

In any case, the prevalence of black flies in the Upper Peninsula revolves around their breeding habits and development. So, knowing this info can help with understanding when and where these pests are at their worst.

Typically, Upper Peninsula black flies mate in the late spring. After feeding, the females can lay 200 to 500 eggs in a single batch. Most of them lay eggs in streams and rivers — only clean, well-oxygenated moving water will do — but some lay eggs on wet surfaces, such as blades of grass.

Submerged in running water, the eggs attach to rocks and other objects with silken threads that extrude from glands. Most black fly eggs hatch in four to 30 days, which is followed by one to six months of larval development.

NOTE: Some species spend winter in the egg stage, hatching when the water warms to 40 or 50 degrees Fahrenheit in early spring and transforming into adults in late spring to early summer after being laid.

The final larval stage sheds to reveal a non-feeding pupal stage that mutates into a flying adult in four to seven days. The adult flies only live for a couple of weeks — two or three.

As a result of this pattern, some black fly species complete several generations of breeding and development in a year, rapidly growing in number.

Movement South

While breeding and development patterns have a major impact on when and where black flies emerge, human activity is a factor as well. For instance, improved water quality in Michigan’s Lower Peninsula has lured black flies farther south than they usually go.

Also, concrete-lined stream channels and dams are excellent places where black fly larvae and pupae can develop.

Tips for Keeping Black Flies at Bay

Biting black flies in Michigan’s Upper Peninsula can be so extreme that it disrupts your outdoor adventures. However, they don’t have to be a huge problem if you prepare ahead of time. You can use these tips to protect yourself (and your pets) from bites.

Wearing Protective Clothing & Gear

One of the best things that you can do to keep black flies from biting you is to wear the right clothing and extra protective gear.

Long Pants & Long-Sleeved Shirts

Since black flies can’t bite through clothing, you should wear long pants and long-sleeved shirts, tucking your clothes into each other to minimize openings. Avoid shirts with button holes, too, because they could crawl inside — zippered clothing will protect you better.

According to scientific studies, black flies are attracted to dark colors — including black, blue, brown, and purple — so wearing light colors is the better option.

Bug Hats

Also, you’ll want to cover your head, and a bug hat — like what beekeepers wear — will do the trick. The netting will protect your ears, eyes, and mouth while still allowing you to see through. Additionally, it will prevent the flies from getting tangled in your hair.

You can get a bug hat on Amazon before you travel. Or, you can stop at Down Wind Sports in Houghton or Munising or at Sport Check in Sault Ste Marie. Just be aware that the netting can be hot and less breathable than if you aren’t wearing one.

TIP: To further protect yourself from black flies, you can get screened tents and canopies for camping and electric fly swatters.

Using Natural & Commercial Black Fly Repellents

The most effective way to repel black flies is to spray your clothes — including your bug hat — with an insect repellent that contains DEET. It can deter other insects from approaching you too. Wondercide makes repellents for humans and pets and is often recommended for deterring black flies.

Many retailers offer insect repellents, and you can purchase some at your local sports store or Amazon before your Upper Peninsula trip. If you’re already on the road, stop by Wilderness Sports in Ishpeming, Superior Outfitters in Marquette, or Dunham’s Sports in Houghton and Marquette.

If you don’t want to use a DEET-based bug repellent, you have many other options. For example, you can drink 1 ounce of apple cider vinegar, which creates an odor that humans can’t detect but that black flies don’t like. Some other options that locals and visitors suggest include:

NOTE: Since bug repellents don’t always work, it’s important to use them alongside wearing protective clothing and gear.

Other Deterrents

In addition to using certain scents and bug spray, black flies don’t like smoke. So, staying near a burning fire — especially while camping — can keep these pests at bay.

And, black flies are very strong fliers, which is why they don’t feed on windy days. So, having a few strong fans nearby will prevent them from getting to you.

Avoiding Attractants

Along with doing things to deter black flies, you can avoid doing things that attract them. The main thing to avoid is sweet-smelling body care products — aftershave, hair spray, lotion, perfume, shampoo and conditioner, and soap. Opt for products that smell like lavender, pine, or vanilla instead.

TIP: Black flies don’t enter buildings to feed, so you can get some respite when you’re dining and shopping in the Upper Peninsula.

Lake Superior - Munising, Michigan
Lake Superior | photo via Lisa Hogan

How to Treat Black Fly Bites

The painful bites from black flies in Michigan’s Upper Peninsula can bleed and swell up because the insects slash the skin open and suck up the pooled blood. Some bites can swell to the size of golf balls.

The bite site can remain itchy for weeks, and an allergic reaction can make these symptoms worse. If there’s a possibility that you’re allergic, you could carry an antihistamine lotion or other allergy medicine with you.

No matter what, there are some things that you can do to improve the healing process after a black fly bite. We recommend taking these steps:

  1. Wash the site of the bite with warm water and gentle soap.
  2. Apply a gentle topical agent that reduces irritation, such as aloe vera, calamine lotion, and witch hazel.
  3. Avoid scratching to prevent the site from getting infected and further irritated.

Other Biting Insects in Michigan’s Upper Peninsula

While black flies seem to be the most annoying, they aren’t the only biting insects that you’ll come across in the Upper Peninsula. Here’s a quick look at these other bugs.

Stable Flies

Stable flies have checkered patterns on their bellies, dark stripes on their backs, and stiletto-like proboscis. They are common at the beaches within the Pictured Rocks National Lakeshore from June through July.

Since they target ankles and legs, tuck your pant legs into your socks. Unfortunately, bug spray doesn’t deter these insects.

Deer Flies & Horseflies

Deerflies and horseflies come in a variety of types. Generally, they have patterned wings and brightly colored eyes. The bigger the flies are, the drabber black or brown they are in color. Sometimes, they have clear wings and light spots as well.

These flies tend to appear from June to August, typically as the black fly season dwindles. The female flies are noisy as they fly in fast circles. And while deerflies don’t leave the shore, horseflies don’t mind going after people in the water.


Also called biting midges and punkies, no-see-ums are usually smaller than 3 mm and look like short-legged mosquitoes. While the majority of species only eat nectar and bite other insects, only a few species bite humans. If you see any, it will probably be in June and July.


Searching for blood meals from early spring to late summer, female mosquitoes are very common throughout the Upper Peninsula.

It’s essential to protect against these bites as much as possible because these insects transmit various diseases. DEET-containing sprays and protective clothing work the best.

Deer & Wood Ticks

Deer and wood ticks might not be insects, but these tiny arachnids bite humans and pets alike. While wood ticks have white markings on their backs, deer ticks don’t. These biting arachnids are present in a range of habitats from early spring through early fall.

Like mosquitoes, it’s important to protect yourself against tick bites because they can transmit diseases such as Lyme Disease. To do that, check your hair and clothing after exploring forested areas.

Sugar Loaf Mountain - #Mittentrip Marquette - The Awesome Mitten
Sugar Loaf Mountain | photo by John Kalmar

Enjoying the Michigan Upper Peninsula Despite the Black Flies

While black flies in Michigan’s Upper Peninsula could put a damper on exploring the region, it doesn’t have to. With proper preparation, you can still enjoy all of the awesome things to do in the Upper Peninsula.

In the end, we hope that you’ll see the bug problem is minuscule compared to your overall experience and the memories you’ll make.

One Comment

  1. Nice! I disagree with one point though. I wore a woven brace on my knee while seeing waterfalls. Despite insect repellent and netting, I was eaten alive and had no fewer than a dozen bites under the brace and under my jeans! Will try vaporub this year! Even bug bites won’t keep me away from the beautiful UP!!

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