Black Fly Bites

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Black Fly

Mark span, CC BY-SA 3.0 via Wikimedia Commons

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Black fly season means black fly bites. Ugh! Here’s when to watch for black flies, how to avoid them, how to repel them, and how to treat their super-itchy bites.

Small and ferocious and intensely annoying, black files — also known as “buffalo gnats” and “turkey gnats” — are the bane of hikers and outdoorsy types in the northeast United States for several weeks each year.

Black Fly Season

Late May and early June is peak black fly season in Hudson Highlands, Catskills, and Adirondacks.

But the season can start earlier and run longer.

I’ve heard people say the black fly season runs from Mother’s Day to Father’s Day, but that’s only a rough guide; Nature does not run on our schedule.

Black flies start buzzing in The Catskills mid-May, and in the Adirondacks a little later.

The Adirondack black fly season is particularly insane. Down in the Catskills, it’s not quite as bad. Some regular ADK hikers switch to The Catskills for the duration of the black fly season.

Where Are The Black Flies?

Black flies love the same places that mountain hikers love: forests and streams.

Black flies are most often found near streams — which includes a lot of the Catskills, and basically all of the Adirondacks.

Females lay their eggs exclusively in running water. Black fly eggs hatch underwater and the larvae attach themselves to rocks. After pupating underwater, the flies hatch and ride to the surface on a bubble of air before flying away.

The further you can get from water, the better. (Good luck with that.)

Black Fly Bites

Black flies will most often bite your head, neck and face — but any exposed skin is a target. If you wear a teeshirt and forget to apply bug repellent to the backs of your arms, that’s where they’ll getcha. If you wear shorts in black fly season, you’re crazy.

Black flies cut a small hole in your skin with their gross fly mouthparts, and then use gross fly anticoagulant, histamines and enzymes to make sure your blood stays flowing. Your body does not love being a fly restaurant.

For most people, black fly bites are fairly painless. Thankfully, in the USA at least, black flies don’t transmit serious disease to humans.

Black Fly Fever

However, if you’re unlucky enough to be allergic to black fly bites, the reaction can be quite intense. Bites can swell to the size of a golf ball and be quite painful.

You may experience “black fly fever” which can include headache, nausea, fever and swollen lymph nodes in the neck.

How Long do Black Fly Bites Last?

You probably won’t notice the bites themselves on the trail. I never notice them until they start itching later. And they will itch. It really is the worst.

For me, the itching intensifies over time. It feels worst about 48 hours after the initial bite.

This after-bite-anti-itch-gel looks interesting and gets great reviews; I haven’t tried it yet.

If you pick up enough bites, and the scabs form just right, you can do a pretty good impression of a plague victim.

Black Fly Bite Treatment

I carry some alcohol swabs as part of my basic hiking kit on every hike. They’re pretty great for cleaning up and soothing minor injuries like nettle stings and black fly bites.

Washing the area with soap and water will also reduce the risk of infection. After washing with soap and water, apply basic topical treatments…

  • Cooling with ice
  • Calamine lotion
  • Aloe vera
  • Antihistamines, either in tablet form or as topical ointment
  • Hydrocortisone anti-itch cream
  • Vinegar
  • Witch Hazel

The above remedies are pretty good. But you will still get itchy. Try not to scratch. Scratching increases the risk of infection. You will not be able to not scratch. But do try.

Black Fly Bite Prevention

Here are your ten best prevention options…

  1. Don’t hike during black fly season — as an option, this sucks, but many people significantly dial down their hiking plans during black fly season;
  2. Wear light-colored clothing — black flies love dark colors;
  3. Wear long-sleeved tees and full-length hiking pants;
  4. Apply a bug repellent like Off! to your clothes, and/or the more natural Repel which you can apply directly to your skin — some people swear by Nantucket Spider and they have Natural Bug Repellent that gets very high ratings and comments on Amazon;
  5. Keep moving — black flies are dumb and slow, and not very good at tracking their victims, so you can reduce the number of dive bombs considerably by just powering right ahead;
  6. Hike on breezy days — black flies are weak fliers and even a light breeze helps keep them away (it also mixes your expelled carbon dioxide with the air, making you harder to track);
  7. Hike during the middle of the day — black flies don’t love the bright afternoon sun and lower humidity, preferring to move around after dawn and for an hour or two before sunset;
  8. Enjoy open areas — large ponds and lakes included — black files prefer woods and flowing streams;
  9. Don’t hike on especially muggy days — what we hate, they love / black flies love humid weather, it’s their absolute jam;
  10. Wear a head net — keep flies and mosquitos off your entire head and neck — if you hit the Adirondacks during black fly season without a head net, you really are crazy.

BTW, you might also enjoy this post about tick prevention during tick season.


The One Good Thing About Black Flies is…

Black flies love clean, healthy, pollution-free streams.

It’s actually a sign of good environmental health that we have robust populations of black flies in our national park lands. We’re doing great!

But literally everything else about them?

Yeah, no…

Image Credit: Mark span, CC BY-SA 3.0 <>, via Wikimedia Commons

Your comments are welcome here…

Hello, I’m Sean

I write independent hiking content to help hikers like you find amazing hikes in the Catskills, Adirondacks, Gunks, Hudson Highlands, Taconics and beyond.

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