By Gabbie Burton
Contributing Writer

State Rep. Christina Sappey hosted a Phorid Fly Virtual Community Update on Monday, March 23 with State Rep. John Lawrence and State Senators John Kane and Carolyn Comitta. The virtual call also included members of the Pennsylvania Department of Agriculture, Penn State University researchers and questions from the public. 

Both the Department of Agriculture and the Penn State team gave updates on their efforts and research to help support southern Chester County communities in their fight against phorid fly infestations. 

“I just wanted to acknowledge the importance of this issue,” said Department of Agriculture Secretary Russell Redding. “We recognize, certainly, it has implications for the mushroom industry in Pennsylvania, there are economic threats the phorid fly poses to growers, but we're also deeply aware of the issue of the interface between growers and the community and that has been part of our guiding effort here to address the issue and to find ways to contain and suppress the phorid flies in in the area.”

Redding announced that the department is issuing a revised quarantine order after the last order was issued in February of 2025. The new order is extended to the entirety of the county rather than just New Garden and Kennett townships as the previous order focused on. The previous order required farms to perform a heat treatment process called “steaming-off” which raises the internal temperatures of the growing houses to a point where phorid flies and larvae could not survive. In addition to steaming off, the new order requires growers to use one of five possible secondary treatments. 

The five possible secondary treatments include insecticide nets, adulticides, predatory mites, parasitic nematodes and the exclusion and inclusion method.

The new quarantine order also features more stringent accountability protocols including mandatory monitoring, documentation and record keeping. Additionally, the department is hiring a staff member to be in Chester County, in contact with the growers in order to support compliance efforts. The department is also allocating $1 million to help financially support growers in adopting the new and required mitigation practices. 

Redding shared that the quarantine order was signed that day, Monday, March 23, with the order being posted to the Pennsylvania bulletin on April 4 and the first report from growers due on April 10. 

Dr. Michael Wolfin, assistant research professor from Penn State, provided results from his research and studies on some of the mitigation efforts, including the parasitic nematodes, predatory mites and insecticide nets. 

In the nematode study, Wolfin and his team had 12 pairs of rooms, one control room and one nematode room, at different farms over the span of three years. They collected fly counts from each room and observed the ratio of emerger flies, or flies from eggs laid in the room, to invader flies, flies coming from outside the room. The nematodes attack larvae, ideally leading to a decrease in emerger flies. The nematode study found a 36 percent lower fly emergence in nematode rooms compared to the control rooms. Nearly 60 percent of growers in the county used nematodes in 2025.

“This is the first intervention that reduces phorid larvae on the farms so this was a big deal in mushroom [Integrated Pest Management] in general,” Wolfin said. 

A similar experiment used predatory mites in nine paired rooms at different farms across a two-year span. Results found a 43 percent lower fly emergence in mite rooms compared to control rooms. 

A third experiment compared larvae found in unwrapped compost to compost wrapped in insecticide nets. An example provided by Wolfin showed the wrapped compost has 28 larvae while the unwrapped compost had 1,645 larvae. Additionally, Wolfin explained that these compost examples were left outside near the swarms people see in the community and not on a mushroom farm. 

The Penn State team then implemented nets on to farms by covering doors and picking lights in the treated nets and found a 52 percent reduction in phorid fly adults in rooms with nets compared to rooms without nets. 

After research was presented public comment began with one community member asking when they will be able to see a decrease in flies. Dr. Troy Ott from Penn State said it will depend on the adoption techniques and successful implementation by the farms. Redding emphasized early intervention in mitigation efforts in order to see best results but neither team could provide a definite timeline on when phorid fly infestation will go down. 

Redding stated that the goal is to see some improvement this year. 

“I feel for the community, I understand the growers have been equally as frustrated with this,” Redding said. “That is our goal. We want to help solve this problem and we’re going to work hard to do it.”

At the end of the meeting Rep. Lawrence shared his concluding thoughts on the update and thanked both the Penn State and Department of Agriculture teams. 

“I'm always hesitant to speak for another elected official, but I do think I can say this evening that I speak for everyone on this call, that we thought it was very important to make these leaders – and these really are the top people in academia and in government here in Pennsylvania when it comes to agriculture – directly available to provide an update, right from the horse's mouth, so to speak, on where things stand,” Lawrence said. “I can tell you that there is bipartisan support, not just from the legislators on this call, but from our colleagues across the state to continue this critical research.”