There’s always a lot going on in Vermont. But one of the main topics of conversation this summer — at least in some towns — is not politics or school funding policy. It's deer flies — and why there are so darn many of them.
That’s certainly the case in Monkton, where I live. The deer flies are so bad this year, neighbors have complained that they can’t garden, can’t play on their swingsets, and struggle to take their dogs for walks. Our community Facebook page has been full of questions about why the deer flies are so bad and good natured tip-swapping for how to avoid getting bitten. (One neighbor even left some deer fly sticky tape in my mailbox for me.)
So once I had convinced Vermont Public that this was a news story worth reporting, I called the state entomologist, Judy Rosovsky.
I told her about my very scientific research (posting on social media and reading the comments) and my conclusion: This is the worst year for deer flies anybody can remember.
Her reply?
“Well, people have short memories.”
Crushing.
“However, I do happen to agree that this is a very bad year for deer flies.”
Vindication!
But, of course, you can’t end a reported story there, so I asked Rosovsky why the deer flies are so plentiful. Unsurprisingly, when it comes to insects, it’s a combination of moisture and temperature.
“In this case, deer flies like to breed near water or saturated soils or moist forest floors,” she explained. “So we had a wet spring, and they like moisture, and then it was hot, and they like hot and… badoom, there they are."
And they're all over Vermont. My research methods had uncovered commiserating complainers throughout Addison County, the Northeast Kingdom and the Upper Valley, plus a plug for the flies being even worse in the Adirondack Mountains of New York. Rosovsky did some research, too.
“I, too,” she reassured me, “use the scientific method of looking online for comments to see whether this was a regional phenomenon or just Vermont. And it does seem that up in eastern Canada, they're having a horrible year, too.”
The deer flies that are biting you this summer didn’t just appear out of nowhere. They overwintered as maggots and emerged in their adult form when the weather warmed up.
Males mostly eat pollen and nectar and have weak mouths. (You don’t need to worry about them.) But in order to develop their eggs, females need the protein and fats only a good swig of blood can provide. And their mouth parts are a thing of horror: two sets of sharp scissor-like blades.
“They're really slashers,” Rosovsky told me. “They're going to make an X-shaped incision on you with those mouth parts. And then they have another mouth part that laps up the blood.”
And they’re not picky — they’ll go for your dog, or for a horse, a cow, or, as their name suggests, deer. Pretty much anything prancing around in the woods or fields with blood in its veins is fair game.
They're really slashers. They're going to make an X-shaped incision on you with those mouth parts. And then they have another mouth part that laps up the blood.Judy Rosovsky, Vermont state entomologist
Deer flies are not stealthy. They are fast, bigger than house flies but not as big as horseflies, and buzz loudly in their approach. You can recognize them by their fighter-jet shape, stripey wings, and big colorful compound eyes. They recognize you using chemical sensors to sniff you out from afar. And their sharp eyesight helps them focus in up close. Some actual scientific research has shown that biting flies are attracted to the color blue, which brings us to what you can do to avoid getting bitten.
“Well, let's see. You can stay indoors. You could do the deer fly swat dance," Rosovsky said. "You can whirl something around your head. You could go for a walk with a taller companion who's wearing blue, who has a good chemical odor.”
But not the chemical odor of bug spray. The jury’s out on whether bug sprays, including those with DEET, do anything to deter these biters.
The jury’s still out on a lot of things, it turns out, when it comes to deer flies. There are 29 known species in Vermont alone, and more than 250 in the United States, but they’re not well-studied.
“Basically, if it's not a public health threat, it's not going to get that much attention,” Rosovsky shrugged. “And being annoying does not constitute a public health threat.”
As if on cue, I felt one on my arm. Before I could react, Rosovsky reached over and smacked it.
“Sorry!” she exclaimed immediately. “I didn't mean to whack you in the arm.”
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But I’d rather be smacked than bitten. Those bites pack a punch, and some people find they swell up and itch for days if the deer fly gets them before they can get it.
And in spite of her position as official state insectophile, Rosovsky doesn’t discourage a little personal pest control.
“After being bitten by them, I really like to kill a few and retaliate, and I know that's not a value I should be promoting. But the good thing is, there's room enough for us all to have an opinion about insects.”
And whatever your opinion on deer flies, take heart: their numbers peak around the end of July, so you don’t have too much longer to suffer.
