What is biting me (Martha’s Vineyard edition)

August 30, 2018 4:22 PM

At two different beaches (Joseph Sylvia State Beach and Lambert’s Cove) on Martha’s Vineyard this week, we have fallen victim to some kind of biting fly. What is it, why does it seem to like us so much, and where can we go to be free of them?

They look like an ordinary house fly - same size, same color - but they keep landing on us and if they stick around long enough we definitely feel something like a sting or bite. They aren’t greenheads. I think they’re too large to be sand flies or black flies, and too small to be horse flies. What are they??? And bonus question, why do they seem to be targeting us? Everyone else on the beach appears to be unmolested while we’re fighting off numerous flies. Double bonus question: is there a beach we can go to on our last day here where we won’t encounter them?

posted by lomes to Science & Nature (9 answers total)

Could they be deer flies? They look a lot like house flies at a glance, but are in the same biting fly family (Tabanidae) as horse flies and greenheads. We definitely have them on nearby Duxbury Beach in the summer and they're obnoxious. They don't like DEET or other insect repellents, but personally my solution is just to go into the water when they start bothering me. Gives me an excuse to take another dip.
posted by Anticipation Of A New Lover's Arrival, The at 5:18 PM on August 30, 2018 [1 favorite]

Best answer: Seconding deer flies. They will track you in the water, even. We came across a new repellant, called PiActive, which is effective against ticks and mosquitos, and contains no DEET. Check it out, it may be worth a try.
posted by Enid Lareg at 5:24 PM on August 30, 2018

Best answer: I just got swarmed by those today. What I learned is that the wind direction has a lot to do with whether they’re a big problem or not. Wind off the ocean is good, wind towards the ocean from land/bay is bad. I heard that deet, light colors helps but I tried deet and long pants/light colors and neither helped much unfortunately (although 30% deet worked better than 15%). I’d look for wind forecasts, stronger breezes off the Atlantic, to find your beach.
posted by ch1x0r at 5:44 PM on August 30, 2018 [1 favorite]

Best answer: They aren't the deer flies or green heads I know.

Some locals are saying "stable flies" -- which I doubted but now I read up that they like seaweed and they look similar. Stay as close to the water as possible and away from any seaweed on the beach.
posted by beccaj at 6:53 PM on August 30, 2018

Best answer: (and they were also saying they normally don't show up until September but are early this year)
posted by beccaj at 6:56 PM on August 30, 2018

These really sound like black flies to me.
posted by Toddles at 10:57 PM on August 30, 2018

Response by poster: They don’t quite look like the images of deer flies that I’m seeing but they do look like stable flies! What a bummer, I thought we’d be safe from biting flies this late in the summer. Sadly, they are not repelled by deet and were definitely tracking us into the water. I guess we’ll try one of the Atlantic beaches today and be ready to beat a quick retreat. Thanks all!
posted by lomes at 6:17 AM on August 31, 2018

Could be horse-flies. Basically bigger deer-flies.
posted by that's candlepin at 9:41 AM on August 31, 2018

PiActive contains picaridin, my favorite insect repellent. Very effective, much ness nasty than DEET, doesn't dissolve plastics, wreck lens coatings, and damage technical fabrics the way DEET does. It's relatively new on the market. Highly recommended, I order mine on Amazon.
posted by Anticipation Of A New Lover's Arrival, The at 6:51 PM on August 31, 2018