From Rogers Park to Calumet, many people in the Chicago area are reporting a surge in flies.
Are there more flies, especially ones that bite?
The public health departments of Chicago and Illinois don’t track biting flies. But anecdotally, they seem ubiquitous. Social media is buzzing with people lamenting getting attacked by flies everywhere from Belmont Harbor to Logan Square.
“Today at a park in West Town I got swarmed by like seven flies after sitting on the ground for less than five minutes with my dog. Those bites are no joke,” wrote one Reddit user this week.
Another Reddit user had to leave Oak Street Beach, “because there were hundreds of flies that kept landing on me and staying on my skin. Felt like tiny needles. I’ve never experienced this at the beach.”
Lifeguards at lakefront beaches have been spotted wielding flyswatters and flies are swarming dogs on walks.
Why are there more flies?
Very wet and hot weather in recent months could be a factor.
This summer, the Chicago area has seen some of the most severe storms in recent years. It has also been very hot, with several heat waves.
Wet and warm conditions are typically good for breeding insects. But Nina Salem, founder of the Insect Asylum in Avondale, said favorable weather conditions vary for different species.
Yet Salem noted that she and other wildlife rehabilitators have been seeing a big uptick of “fly strikes.” That’s when flies lay eggs on animals such as squirrels and raccoons. After hatching, flies burrow into animals, alive and dead.
Salem cautioned against washing any affected animals because water will trigger hatching of eggs, which look like white rice.
What kind of flies are we likely seeing?
There are many kinds of biting flies, according to the Illinois Department of Public Health.
But the stable fly is a likely culprit because they peak in late summer and early fall. It’s gray with four dark stripes behind the head. This bloodsucker “will fly several miles to bite livestock (hence the name), pets and people,” said the department’s website. “They typically bite in early morning or late afternoon and often attack the ankles, inflicting a sharp, stabbing pain.”
Stable fly larvae “live in and eat decaying vegetation that washes up along the shore,” according to the National Park Service in Michigan’s Pictured Rocks. They don’t transmit disease to humans, but “are annoying enough to drive people away from beaches.”
Stable fly outbreaks have occurred along the shores of Lake Michigan, Chris Stone, medical entomologist at University of Illinois Urbana-Champaign, wrote in an email. “This species is considered to be more abundant in years with high rainfall. So a peak this year would make some sense,” he said.
Other biting flies include deer flies, which are most abundant in the spring, as well as horse flies. Some horse flies are entirely black, while “greenheads” are light brown with shiny green eyes. Larvae live in water or moist locations.
Are fly bites especially painful?
They can be.
Stable flies suck blood through a pointed proboscis. “They have bayonet-like mouthparts with rasping teeth at the tip that they use to cut through or abrade the skin to create a pool of blood on which they feed,” Stone explained..
Deer and horse flies bite with “scissor-like mouthparts that cut into skin, causing blood flow which the flies lap up,” according to the Illinois Department of Public Health. This crude blood sucking can be especially painful.
What are officials doing about the flies?
Chicago Parks District “has not received an influx of concerns regarding the presence of biting flies, mosquitos and other insects in our parks,” Michele Lemons, director of communications, wrote in an email.
The parks department hasn’t seen park use drop. “In fact, for many of our programs, we saw an increase in participation this summer,” said Lemons.
But on Friday morning, Lake Forest Parks and Recreation department treated Forest Park Beach with an “EPA-approved product.”
The department said on Facebook, “While we can all agree our beach is amazing, the latest increase in fly activity is not!”
Indiana Dunes National Park warned about an outbreak of biting flies on Facebook, according to WBBM News Radio in Indiana. Park staff noticed a surge in biting flies on some eastern beaches about a week ago.
On Thursday, the Illinois Department of Public Health said it’s working on updating guidelines on managing flies and bites.
What can I do?
Most insect repellent doesn’t work on stable flies. Since they target legs and ankles, the National Park Service recommended wearing long pants and socks – not ideal for the beach.
In any case, stable flies can pierce through clothing, according to fly control company Spalding Labs.
Salem noted that parasitic wasps can eat flies. But if fly predators aren’t handy, she and Stone suggested treating clothes with permethrin, a chemical insecticide.
How long will this last?
A stable fly’s life span is 20 to 30 days. In the U.S, their peak season is July through September. But they can remain into October in warmer regions.
This summer, the Chicago area has endured heat waves, tornadoes, rainstorms, wildfire smoke and deafening cicada choruses. Now it’s biting flies. What’s next?