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Greenhead Flies at Cape Cod Beaches: You Can Outsmart Them!

Have you heard tales about greenhead flies at Cape Cod beaches?

Not to worry! After decades of battling these biting green-eyed menaces, I've learned how to (mostly) outsmart them. 

So let me fill you in on what they are, when they’re a problem, and how to avoid becoming their luncheon of choice.

What are Greenhead Flies?

You'll know it's a greenhead fly if:

• it's about twice the size of a normal house fly;
• it has a honey-colored body and large, iridescent green eyes;
  
• it's persistent, coming back for another try if it doesn't get you the first time.

Greenhead Fly Season on Cape Cod

Prime beach season on the Cape is also prime greenhead fly season. (Mother Nature has quite the sense of humor, doesn't she?!)

A perfect day at the beach on Cape Cod. (Or is it???)

Some locals will tell you the greenies come out with the full moon in July, and they're gone by the full moon in August. 

But I'm here to tell you: that's not entirely accurate.

Last year, I whacked my first greenhead the third week in June. And I was still seeing them in early September. 

Granted, they weren't as prevalent in June or September. But they were still around.

Where You'll Find Greenhead Flies

Short answer: mostly around marshy areas. If there's a salt marsh nearby, there's a good chance greenheads will be nearby, too.

You’ll see these blue boxes in marshes around the Cape. They’re greenhead fly traps.

How to Avoid Greenhead Fly Bites

Nothing is foolproof. But there are some things you can do to minimize your chances of a greenhead encounter: 

1. Embrace the wind. On a still day, greenheads will travel a mile or more to find a meal.

But they're not strong flyers. So a windy day tends to keep them at bay.  

2. Choose your colors carefully. Remember the blue greenhead fly trap I showed you earlier?

For some reason known only to bug scientists, greenheads are attracted to the color blue. 

I'd opt for a different color beach umbrella and pop-up tent — especially at a beach with a marsh nearby.

3. Don't count on bug spray to keep them away. 

I've tried everything from Avon Skin So Soft to Deep Woods OFF!, as well as many of the other things people recommend online. I've even resorted to fly sprays made for horses.

So far, nothing I've tried has consistently deterred the green-eyed devils.

What if You Do Get Bitten?

You can take all the precautions, but still get nailed by a greenhead fly.

What happens when one bites me? Honestly, not much. Two seconds of pain, a tiny droplet of blood — and some very salty language because I didn’t get it before it got me.

My husband, though, is a totally different story. He usually ends up with a small welt that itches like crazy. 

So here’s what we do:

• Wash the welt with soapy water when we get home.
• And if he can’t stop scratching, I whip out the anti-itch lotion.

One last tip: If greenheads are bothersome at one beach, try another. Cape Cod has a lot of beaches, and moving to a different one a mile or two down the road is usually all it takes.

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