On Thanksgiving 2015, Margo Woodacre had to send her family home on empty stomachs. A month later, Barbara and David Runkle were unable to put up their Christmas tree. In the years since, neighbors have worn out vacuum belts, spent untold amounts of money on black lights, and become amateur experts on homeopathic pesticides.

All because of a species of fly whose proliferation has stumped researchers. A fly inherently tied to mushrooms, the cash crop that serves as the backbone to Chester County, to the tune of nearly $400 million in the last fiscal year.

Now, thanks to a $90,000 grant from the state, scientists at the local Pennsylvania State University extension office will embark on a new, experimental method of combating the flies: the hiring of a hybrid researcher/community liaison.

"People have moved away. People are selling their homes, taking a loss," said Barbara Runkle, a resident of Harrogate, a retirement community near the Delaware state line in Landenberg. "When it's 'high-fly season,' you can't even turn the lights on. We came here to live our lives, and this is an all-encompassing issue."

Reports of mushroom phorid flies harassing people in the county have been persistent for three years now. Horror stories abound about thousands of flies being vacuumed off windows, coating sticky traps placed in basements, and pushing families to spend as little time at home as possible.

The insects' eggs are usually laid in fertile mushroom soil, and the flies grow alongside the crop. They've been reported in other states where mushrooms are grown, but never in these numbers, researchers say. In Chester County, they're in full force by midsummer, peaking sometime around September.

"The folks at Penn State have a scientific process, they have to test their hypotheses, and find conclusions," said Joe Miscione, another Harrogate resident. "That's all well and good, but that takes five years. We need an answer now of what we can do to alleviate some of this."

Mushroom phorid flies, seen here inside a Kennett Square mushroom house, have been swarming inside homes in southern Chester County for three years.
ED HILLE / FOR THE INQUIRER
Mushroom phorid flies, seen here inside a Kennett Square mushroom house, have been swarming inside homes in southern Chester County for three years.

The Harrogate residents have been particularly vocal, but they're not alone: Their counterparts in Kennett Square, Lower and Upper Oxford Townships, and Lincoln University have all made similar complaints since the insects started crawling around in record numbers.

Those reports have all made their way, in one form or another, to Tom Baker and Nina Jenkins, researchers and professors of entomology at Penn State. Sometimes as dead flies delivered to their mailbox in State College.

And while the two have received funding in years past to study the flies' ecology and behavior, this latest grant is unique, the first of its kind that the two have seen in their decades of work studying insects.

"We have all our research mapped out over the next couple of years, but meanwhile residents are living with this problem," Baker said. "What we have never had funding to do, or the infrastructure for, is communicating with residents and assisting them with their concerns."

The 10-month grant from the state Department of Agriculture, announced last week by the university, funds the hiring of the new entomologist and helps cover the cost of producing educational material for residents, according to Baker. It also opens the door for further funding of this nature in years to come.

They envision this new entomologist – whom they hope to hire by July – as an "expert voice," one who can have a consistent presence in the community. Because, as much as Baker and Jenkins have tried to attend the various community meetings about the phorid fly issue, their main focus has been on their research.

"Whenever there's a discussion about mitigating the flies, different residents say they've had different success with different methods," Jenkins said. "But if there are methods that do seem to be working for multiple residents, this person could guide those conversations. And because that person is a scientist, they could police those discussions to make sure the methods are reliable and not just smoke and mirrors."

Since 2015, which residents generally agree to be the arrival of the worst of the phorid flies, those community meetings have gotten progressively more involved. The residents of Harrogate formed the Phorid Fly Action Committee, drawing the attention of State Sen. Andrew Dinniman, State Rep. David Roe, and local township officials. It's a collaborative effort, with mushroom growers also having a seat at the table.

And while the eclectic group can all agree that flies are a nuisance, no one seems clear on why they're swarming in the homes. But theories abound.

Phorid flies are always present, in some capacity around mushroom farms, according to Eric Toedter, the manager of research and development at Southmill Mushrooms in Kennett Square.

Eric Toedter, the manager of research and development at Southmill Mushrooms in Kennett Square, says it's not entirely clear why mushroom phorid flies are swarming in such high numbers around Chester County.
Ed Hille / For The Inquirer
Eric Toedter, the manager of research and development at Southmill Mushrooms in Kennett Square, says it's not entirely clear why mushroom phorid flies are swarming in such high numbers around Chester County.

He's seen them in Chester County since he arrived in 2010, and his company has records of their presence going back to at least 2006. Their exponential increase in the region comes suspiciously close to the Environmental Protection Agency's ban on diazinon, a pesticide used to control various species of flies.

The EPA banned the substance for residential and commercial use in 2004, and halted all agricultural use in 2012, according to Laura Phelps, a consultant for, and former president of, the American Mushroom Institute. The agency deemed it too harmful, not for consumers or the mushrooms themselves, but to the workers in the houses.

Others in Chester County think the flies' arrival is owed to development. Some residents in Harrogate say the worst of the flies came when construction began on Harlow Point, another, similar community yards away from their own.

But none of this is definitive, according to the Penn State researchers. What everyone can agree on, however, is that it's an issue worth investing time and resources into.

"It's not just Harrogate that has this problem," Margo Woodacre said. "We love this neighborhood. This is not an issue that's just here. This is a Chester County issue."