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Greenheads | Learn about Greenhead Flies, the Beasts of the Northern Wild

Greenheads | Learn about Greenhead Flies, the Beasts of the Northern Wild
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What’s up with this bug? Clearly it’s a robust type of horsefly (the name is a tip-off), and it certainly outweighs its relative the deerfly, although both biters belong to the same fly family, Tabanidae. And “greenhead” obviously refers to its enormous green eyes, laced with bands of iridescent red or purple.But above and beyond these physical characteristics, and the fact that greenheads will indiscriminately attack horses, cows, dogs, hogs, and deer, this fly is notorious mainly for one thing: the pain it inflicts in large numbers on beachgoers at the height of summer. Make that two things, because like The Terminator, this fly is relentless. It will not stop until someone pays the price.

Stories of encounters with greenheads have a dramatic quality usually reserved for plays written by one-name ancient Greeks. But the blunt truth is that these creatures can ruin a day, or days, at the beach.

Often during peak greenhead season–generally early or mid-July to mid-August–beaches will post warnings about fly conditions, like some weird variation on the surf report. At Crane Beach there’s another sign, too: No Refunds. But it’s not about singling out one beach or another; any gathering spot near a salt marsh–beach, restaurant, or home–is potentially vulnerable. Sometimes it’s just a matter of degree.

“All salt marshes on Cape Cod provide habitat for greenhead flies,” says Gabrielle Sakolsky, entomologist and assistant superintendent at the Cape Cod Mosquito Control Project. “Our largest marshes, adjacent to the large barrier beaches of Sandy Neck and Nauset, are the worst, because they have the largest amount of larval habitat. There are no immune spots.”

If that’s the case, I suddenly have more questions. Can greenheads be outsmarted? What makes them so rabid in the first place? Why is the pain so fierce? And don’t we have any options?

In search of answers, I’ve found myself knee-deep in a salt marsh with John Stoffolano, Ph.D., professor of entomology at UMass Amherst. It’s early August: prime tabanid time.

Every summer, Dr. Stoffolano and his students head into the dark heart of greenhead territory–the broad and glorious salt marshes that spread out around Pine Island, in Newbury, Massachusetts, not far from Crane Beach. Here they collect thousands of flies from the shiny black wooden boxes that stagger on slender legs across the marsh, like dark, square animals imagined by a Cubist carpenter. Back at UMass, they conduct research on greenhead behavior and physiology. “We’re the only ones doing this kind of work,” Dr. Stoffolano told me when I first visited his office in Amherst, months earlier. “At one time there was a lot of interest.”

That was before scientists learned that tabanids do not in fact carry Lyme disease or AIDS, that they’re merely a horrible nuisance. But in the 30-plus years he’s been researching these flies, Dr. Stoffolano has learned a lot, and he’s got the office to prove it. Bookshelves overflow with the chaos of his profession–research materials, scientific papers (many his own), and reference books–the contents spilling onto the floor, the desktop, any available surface.

In sharp contrast to its occupant, who is neat, self-contained, and, it turns out, pretty funny, with an adventurous streak. Tales of tsetse flies in South Africa, encounters with biting beach flies in the Seychelles, and experiences at a Zulu healing ceremony weave in and around talk of greenheads. His mother is part Mohawk Indian, and Dr. Stoffolano’s interest in indigenous cultures and insects has gradually evolved into a college course on cultural entomology, in which he uses insects to teach diversity, while incorporating references to art, music, mythology, and archaeology. Traces of Indiana Jones, minus the bullwhip.

Please Note: This information was accurate at the time of publication. When planning a trip, please confirm details by directly contacting any company or establishment you intend to visit.

Annie Graves


Annie Graves


Annie Graves is a regular contributor to Yankee. A New Hampshire native, she has been a writer and editor for over 25 years, while composing music and writing young adult novels. Find out more about Annie at

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4 Responses to Greenheads | Learn about Greenhead Flies, the Beasts of the Northern Wild

  1. Kathy Woinson July 12, 2014 at 12:58 pm #

    Great article I just read as I had to retreat to indoors because of how vicious the greenheads are today. I thought that they arrived on the new moon the end of June & were gone by the full moon high tide in July, which is tonight! Guess maybe that’s not true, maybe it’s the full moon in August?? Sure is a miserable few weeks and they certainly are nasty bighters!! Very informative article though,

  2. Helen Rankin August 4, 2014 at 8:41 am #

    I go to Cape Cod and some days green flies make it unbearable on Nauset Beach. Then we have Plovers nesting resulting in the closure of the beaches. It’s maddening!!

    • Michelle August 6, 2014 at 11:29 am #

      Hi Helen… Do you know if the green heads are still bad right now? Michelle :)

  3. Laura F. August 26, 2014 at 11:29 pm #

    I live in South Jersey and the only thing that works for me 100% no greenheads is…when the wind blows from the East (off the ocean). This keeps them at bay, literally. Lol
    The absolute worst time to go to the beach between June-September is when the wind blows from the West (off the land).
    I believe you’ll be fine with little to no flys if it blows from other directions too. IF the wind changes from the West while your there, a few flys MAY appear but leave right when it changes again.
    Since I live close enough to the beach to drive down for a day trip, I just check my Weather App the day before and morning of to see which direction the wind is blowing. I guess for those of you who go to the beach for more than one day on vacation, this method won’t help you that much.
    In that case, I’ve heard from many people that Avon’s Skin So Soft works as a repellent…I think they even have a bug repellent that’s water resistant with SPF 30, and anti-itch relief.

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