To celebrate my 25th birthday a few weeks ago, I went for a trail run in Henry’s Woods in Lake Placid. Unfortunately, I forgot that we were in the midst of a yearly Adirondack tradition — black fly season.
Blissfully unaware, I decided to run while my companion, (my mother) walked. I’m not exactly Usain Bolt, so I kept my pace moderate. I paused a few times to catch my breath, but for the most part I kept moving.
An hour later, we emerged from the woods, and my mother was bleeding. She had been bitten viciously by the black flies. Meanwhile, I had escaped virtually unscathed.
It wasn’t just in the woods where we had to fend off the pesky creatures – like many others in Lake Placid, we collect fresh spring water almost every day at the River Road Spring. While there, my mother and I were swarmed by the black flies, but I still had less bites.
I started thinking about black flies and what measures could be taken to prevent their bites. I had some standard questions – is there any way to repel black flies? What kind of weather do they like? Do certain people attract more black flies? Can you outrun a black fly?
To answer my questions, I emailed the State University of New York College of Environmental Science and Forestry’s Adirondack Ecological Center (AEC). My first question was, “is it possible to outrun a black fly?”
“Absolutely,” said Charlotte Demers, a Wildlife Technician at the AEC. “They can fly approximately five miles per hour, so if you can run a six-minute mile you could likely out run them… The problem is that you have to keep running. Don’t stop. Don’t slow down. Just keep running.”
This isn’t the airtight solution many might hope for. As Demers notes, because they can fly, they can still find a way to intercept you down the trail: “There will always be the black flies that manage to intercept you or get tangled in your hair and make a beeline for the back of your neck.”
So it is possible to outrun black flies (at least temporarily), but there is another way of looking at this situation as well – evasion (leaving their sensory field quickly enough to avoid interception).
I contacted Adirondack Almanack contributor Tom Kalinowski, an ecology and field biology teacher at Saranac Lake High School for 33 years. When I emailed Tom for his take on the question of outrunning black flies. He approached the question from a perspective of black fly sensory capacity, rather than speed.
“I am of the opinion that they lose “sight” of you when you are moving at a relatively fast pace. It takes a little bit of time for this insect to properly identify a potential victim to attack, as they can not expend the energy investigating every form of animal life that moves around them. A creature that is traveling at a faster rate is far less likely to catch the attention of a female in need of warm-blood, compared to a mammal or bird that is stationary, or strolling along at a much slower pace. (Stationary, or slow moving targets are always easier to recognize and hit compared to ones that are in the vicinity for only a brief period of time.),” said Kalinowski.
“This means that if you were jogging along through a black fly infested forest, the individuals lurking in the brush would only get a second, or two to detect your presence and react, which is probably too short of a time frame for these tiny insects. On the other hand, a person ambling along would be on a black fly’s “radar screen” for a much longer time and would give this insect the needed opportunity to respond to the presence of a host.”
Charlotte Demers confirmed this idea: “Black flies have eyes and can see but their range of visual detection is minimal. So yes, if you are moving fast it is harder for them to key in on you. I looked up a more recent article on black fly flight and the maximum they clocked a black fly at was two miles per hour. The same study also had a female of the species continuously fly for over five hours. So you better keep moving because they appear to be very determined.”
What is you can’t or don’t want to run? Are there any repellants that work effectively, or tips that can make you less attractive to black flies?
“Color makes a difference,” said Demers. “We’ve always told our summer students not to wear blue. There have been multiple studies that have found dark colors to be more attractive to black flies (blue, black, red).”
As for repellents, my mom and I purchased “black fly balm” at our local health food store, because with various food allergies and intolerance to chemicals and scents, I can’t tolerate DEET, which according to Demers, is the most effective repellent. “DEET obviously works and is the most effective,” she said. “While the plant based ones can repel them, they are not as effective and need to be reapplied frequently.”
Repellent effectiveness may be mostly mental however, warned Demers. “My motto is that if you think it is effective, than it is. Black fly warfare is mostly psychological.”
What about those who say they tend to get bitten more often because black flies “like them”?
“Yes, some people really are black fly magnets. Studies with human subjects have found that biting rates differed among individuals. In one study with five male subjects, one person was consistently ‘more attractive’ while one was ‘less attractive’ and the other three were intermediately attractive. They also did some manipulations with their CO2 exhalations and found that ‘a human form (silhouette) plus breath odor’ got more of a response then just a human form, a human form plus body odor, or carbon filtered exhalations. So it could be an individual’s production of CO2 in addition to other components of their breath that make them attractive to black flies.”
My last question was about weather. What kind of weather do black flies like? I found my answer in a 2013 essay by Tom Kalinowski.
“Several hours after sunrise and an hour or two before sunset are especially favorable to this small and delicate creature as the air is usually more humid during this period when the sun is close to the horizon. Overcast days and times when a mass of muggy air has settled over the region are other occasions when black flies are active throughout the day. As soon as the air becomes warm and dry, dehydration can seriously impact this small fly. Hiking during the heat of the day when the relative humidity drops to under 30% is the ideal time when black fly season is at its peak.”
So at the end of the day, it can be said that choice of color, speed of movement, and weather can impact the likelihood of being bitten by black flies. Charlotte Demers summed up her best advice for avoiding black fly bites.
“Wear white, run fast, don’t breath (or maybe use a snorkel), and don’t stop running.”
Sounds like great motivation to get in shape, but a friend of mine Lynn Zuliani had another idea. She posted a photo of herself to Facebook wearing a black mesh suit that also covers the head. She tells me she purchased it a few years ago at Blue Line Sports in Saranac Lake.
“It really works,” Zuliani said. “It’s a little hot and claustrophobic, but better than [being] bitten!”
Illustration from The Book Of Camp-Lore And Woodcraft by Dan Beard. Below, Lynn Zuliani of Saranac Lake, NY wearing her black fly suit.