By Blake Jackson
Agriculture Secretary Russell Redding has announced an updated quarantine order aimed at strengthening efforts to control Phorid flies, scientifically known as Megaselia halterata.
This pest has been causing significant damage to mushroom crops in southeastern Pennsylvania, while also becoming a nuisance for nearby residents.
To support compliance, the Shapiro Administration has allocated $1 million through the Chester County Conservation District to assist growers in meeting the updated requirements.
Although these flies do not pose a threat to human health, they can severely impact crop yields. Officials also confirm that neither the pests nor the treatments used to control them affect the quality of mushrooms sold in the market.
The Pennsylvania Department of Agriculture revised its original January 2025 quarantine after gathering feedback from industry stakeholders and monitoring crop conditions.
The updated order expands its scope to include more farms and introduces stricter measures to safeguard one of the region’s most valuable agricultural products.
"The department worked with mushroom industry leaders and Penn State researchers to develop safe, effective ways to control this pest, and demonstrated their effectiveness over the past year. We know these methods are safe and effective, but they only work when every grower is following the best management practices every day," Secretary Redding said.
"By giving mushroom farmers tools to control pests and financial support to help them do it, the Shapiro Administration is showing that we are committed to helping farmers protect their valuable crops so they can continue to produce top quality products to feed Pennsylvania’s economy.”
Effective March 23, 2026, all mushroom growers in Chester County must steam-treat growing facilities and used materials between crop cycles. This pasteurization process eliminates flies, larvae, and pathogens, helping prevent further spread.
Farmers are also required to maintain treatment records and adopt at least one additional control method, such as exclusion practices, biological controls, or insecticides.
Phorid flies thrive in warm, humid conditions commonly found in mushroom houses. Rising temperatures and humidity have worsened infestations, with crop losses reaching up to 40% in some cases.
Photo Credit: istock-guruxoox
Categories: Pennsylvania, Crops, Fruits and Vegetables, Government & Policy