By Richard L. Gaw
Staff Writer

The thousands of newcomers to this year’s Mushroom Festival in Kennett Square Borough in September were not the only first-time visitors that populated this popular hamlet in southern Chester County this fall.

During the warm weather months of early fall, borough residents began to flood the Kennett Borough offices with complaints that the phorid fly – the invasive insect known to breed at the many mushroom growing and composting facilities throughout southern Chester County – had begun to proliferate in homes throughout the borough and beyond. It did not take long – by the end of August, to be precise – before Kennett Square Mayor Matt Fetick and members of the Kennett Borough staff began to receive emails and phone messages complaining about the fly’s presence in their homes.

“This year by far has been the worst,” Fetick said of the phorid fly proliferation in the borough. “We have had more people reaching out than ever before and its was very clear and obvious this year that it was different than usual. While the flies can be around in the warmer months of July and August, they typically are worse by the fall because as they breed and continue to grow, they begin to invade homes.” 

Soon after the complaints began filing into the brough’s offices, so did the photographs of the insect that came in from residents that gave clear evidence that homes in the borough were being assaulted. 

Fetick then doubled the efforts to draw attention to the issue when the borough hosted a public meeting in November that gathered 60 residents in attendance and another 100 who tuned in by Zoom. The big question on the mind of many area officials and local residents at that meeting was how to contain and eliminate the phorid fly, not only at mushroom farms throughout southern Chester County but also at private residences that border these farms. 

In an effort to find support, Fetick reached out to State Rep. Christina Sappey, who had worked with then State Sen. Andrew Dinniman several years ago when the phorid fly began to infiltrate homes near mushroom facilities throughout New Garden Township and beyond. In 2021, Sappey held a virtual meeting to share information about the work being done on the problem that invited several experts from the Penn State Mushroom Pest Research Team, Pennsylvania Secretary of Agriculture Russ Redding and local legislators.

In August of 2022, Sappey was instrumental in acquiring state funding to Penn State in the amount of $128,718 to expand the use of new integrated pest management to control phorid flies in mushroom production.

“We are incredibly fortunate to have the talented team from Penn State working tirelessly on the biology and behavior of phorid flies,” she said in a statement. “They have been efficient with the dollars provided to them, squeezing everything possible out of each cent. It is encouraging to see their processes implemented in local farms, and ultimately having a positive impact for mushroom growers and residents.”

‘Significant public nuisance’

According to scientific data, the phorid fly -- Megaselia halterata -- continues to threaten the mushroom farming industry by vectoring fungal diseases and reducing the yields of the crop that has led hundreds of mushroom harvesting and producing farms to experience hundreds of thousands of dollars in losses. In recent years, mushroom phorid flies have also become a significant public nuisance in residential areas in parts of Pennsylvania, Delaware and Maryland.

The window to eradicate the phorid fly is sliver thin, given that its life cycle has only four distinct stages: egg, larva, pupa, and adult; the last stage is very short, consisting of mating, laying eggs, and dying, but during that short time, phorid flies were taking up residence in many of the borough’s homes. 

In years past, the proliferation of the phorid fly was contained and eliminated by farms through the use of Diazinon, an organophosphate that was ultimately banned by the Environmental Protection Agency in 2012 and is currently not available for commercial or residential use. Over the past several years, the Department of Entomology at Penn State under the direction of Dr. Michael Wolfin has been performing laboratory and field experiments to identify alternative effective insecticides and novel control methods to manage this pest. Fetick spoke with Dr. Wolfin in the early fall and learned that despite the absence of Diazinon to mitigate the phorid fly – at either mushroom farms or in residential homes – there has been some encouraging news in the last two years. 

“One hundred percent of his efforts has been focused on mitigating the phorid fly at its source, which are the mushroom farms,” Fetick said. “One of things Dr. Wolfin explained to me was that Pennsylvania went into 2023 and 2024 with no approved mitigation measures for the phorid fly, but while there were no specific plans approved, his department was testing and seeing different results on different farms, and that had some good results.” 

Fetick learned, however, that while two of the four techniques require registration from the Environmental Protection Agency (EPA), the remaining two do not require EPA approval, but will take full cooperation from the mushroom industry in order to get them in the hands of farmers and homeowners. 

“For this issue to be solved, it will take 100 percent compliance [from mushroom farms], because if one farm is doing mitigation techniques, the flies will go to another farm for a source of food and stop at homes along the way,” he said. “Our assault has to be multi-faceted, and we have to get these issues fast-tracked, so I am asking that they accelerate these approvals because of the severity of the issue.

“Of the two [materials] that have been approved, can we get the manufacturers’ ears, in person? Can we hold several community meetings for mushroom growers and get them in the room with the manufacturers and begin to take orders in 2025?”

Fetick has also called for increased funding to allow for research applications of repellents that homeowners will be permitted to use in their homes and has been in contact with Rep. Sappey to seek that funding in Harrisburg. 

Emergency declaration issued for Kennett Borough

Calling the phorid fly infestation “a true emergency in our community and the greater region,” Fetick took the borough’s largest stand against the phorid fly infestation in early December when he signed an emergency declaration calling for “a comprehensive, multi-agency approach to eliminate the phorid fly infestation” by enacting the following six initiatives:

• Pursuing additional state funding to research mitigation controls through Penn State and private entities to reduce and eliminate the fly at mushroom growing facilities and using best practices and products in private residences
• Incorporating educational tools for mushroom growers about mitigation controls
• Enacting state regulations to allow mushroom growers to implement effective and safe pest controls
• Fast-tracking the review and approval of mitigation controls by the state and other regulatory authorities
• Establishing a multi-agency task force made up of representatives from the Pa. Department of Agriculture, the Pa. and U.S. Departments of Environmental Protection and other agencies, representatives from the mushroom growing industry and private citizens, and
• Provide education and information to Kennett Borough and nearby municipalities regarding progress made on each the initiatives

Fetick said that the emergency will remain in effect “until we begin to see solutions.”

“Until we are satisfied that there is a plan to mitigate this issue, the emergency is stating,” he said. “I plan to bring it up at every Borough Council meeting and renew it at every single council meeting so that it doesn’t get lost.” 

The next Kennett Borough Council meeting is scheduled for Jan. 6.

In addition, he is encouraging residents to send him their email address so that they can keep informed of any updates related to the phorid fly issue, and asked borough staff to keep them up to date on the borough’s Facebook page. 

To contact Staff Writer Richard L. Gaw, email [email protected].