Pest Control in Kennett Square: Mushroom Country Flies and Borough Homes

Who serves Kennett Square, and from where

Kennett Square is in southern Chester County, Pennsylvania, which we cover as part of pest control serving West Chester and central Chester County, and it is listed on our Chester County service page with the rest of the county. Our headquarters, and the only address we use, is 153 Silver Springs Rd in Phoenixville, about 28 road miles north of the borough. There is no Kennett Square storefront, so every visit happens at your house.

The coverage is four municipalities that share the 19348 Kennett Square mailing address or border it: the borough itself, Kennett Township around it (including Hamorton), East Marlborough Township to the north (including Unionville), and New Garden Township to the southwest (including Toughkenamon, with parts that mail as Avondale and Landenberg). Kennett Township and New Garden Township are the two townships named in the state phorid fly quarantine order.

Mushroom farms set the pest calendar here

Kennett Township's Resolution 2026-8 counts more than 2,000 mushroom growing rooms in southern Chester County and calls mushroom growing the region's largest agricultural business. The mushroom phorid fly breeds in those rooms. The Pennsylvania Department of Agriculture describes it as a fly that feeds on fungi and reproduces in the dark, humid conditions of mushroom houses, destroying 10 to 40 percent of a crop when it gets established.

When fly numbers build inside the growing houses, adults get out and drift. Penn State Extension notes that wind can carry them several miles, so the farm nearest your house is not always the one sending them. Kennett Township's briefing on the resolution says phorid flies have hurt quality of life for residents within several miles of growing rooms since 2012.

Penn State reports populations spike in September and October, when cooler, humid fall weather lets adults survive outside longer, and that hard freezes knock numbers down over winter. That puts the fly peak in the same weeks as the stink bugs and cluster flies covered further down this page.

The phorid fly record, date by date

Local governments and the state have both acted on the flies. The table lists each public action and the document it comes from.

What a pest control visit can and can't fix

Township officials note that under Pennsylvania law, local governments have no authority over the farms. A pest control company has none either. The source is in the growing rooms, and the steaming-off requirement and the townships' push for more controls are what address it.

Our work is on your house. Penn State says phorid flies cannot breed indoors, because the larvae need growing mushroom mycelium, and adults live only a few days. Every fly indoors got in from outside. We confirm the fly is actually a phorid and not a drain fly or fruit fly breeding in the house, find the vents, screens and gaps they use, and set up light and sticky traps where they gather. That cuts down the flies indoors, but it won't stop new ones arriving from the farms while fall numbers are high. The full breakdown is on our Kennett Square fly control page.

Borough houses versus township subdivisions

The four towns are built very differently, and that changes the non-fly work. Census figures (ACS 2020-2024) show the split:

• Borough homes: 28.7% were built before 1940. Older sills, settled foundations and gaps around old pipe and wire penetrations let mice in. Penn State notes a mouse can fit through a hole about the size of a dime. Our mouse and rat control starts with finding those gaps.
• Township subdivisions: about a third of homes in Kennett Township and New Garden Township date from 2000 or later. Penn State notes termite damage typically shows up 10 or more years after construction, which puts many of these houses in that window now. See termite inspection and treatment.

Fall invaders on the farm and field edge

Phorid flies are not the only thing coming indoors in the fall. Cluster flies develop as parasites of earthworms in soil, so lawns, pastures and field edges around East Marlborough Township and New Garden Township produce them. Penn State says they move into attics and wall voids in autumn and show up at windows on warm winter days. They don't breed indoors either, and Penn State advises sealing cracks around windows, siding and utility pipes rather than treating wall voids, since dead flies there can feed carpet beetles.

Brown marmorated stink bugs start entering houses in September and October, and Penn State notes homes next to woods are at higher risk. With both of these arriving in the same weeks as phorid flies, fall exclusion work on a Kennett-area house covers several pests at once. Our stink bug and fall invader control page explains the sealing approach.

Spotted lanternflies are the other fall insect on local trees and walls. All of Chester County has been inside the Pennsylvania Department of Agriculture spotted lanternfly quarantine since November 2017, and adults lay egg masses from September on. They rarely come indoors, and our spotted lanternfly guidance covers egg mass scraping.

Termites in older borough houses

Penn State Extension notes that eastern subterranean termite infestations usually begin at the basement mudsill and joists, where wood framing rests on the foundation. With 28.7% of borough homes built before 1940, we check sills, porch framing and basement walls for mud tubes, and note carpenter ants or other wood-destroying insects in the same damp spots. See termite inspection and treatment.

How a visit in the Kennett area runs

Every job follows The Davis Inspection Standard, and each step applies directly to the fly problem.

• Identify the species first. A small fly in a Kennett Township bathroom could be a phorid, a drain fly or a fruit fly, and each has a different fix. Nothing is applied until we know which.
• Name the conducive conditions. For flies that means torn screens, unscreened bath and dryer vents, attic gaps and lights left on at night. For mice in borough houses it means the foundation and utility gaps.
• Place treatment where the pest lives, per the label. Traps go where flies gather. Any product goes only where the label allows.
• Set a follow-up. You get re-entry and prep instructions before we start, and a follow-up visit on the calendar, which matters in a fly season that runs for weeks.

Booking service in Kennett Square

Call (610) 935-9130 or use our contact page. Tell us which town you're in and what you're seeing, and if it's flies, catch a few on tape so we can confirm the species. We are licensed with the Pennsylvania Department of Agriculture in the Household and Health Related and Wood Destroying Pests categories, and insured. Details are on our licensing and insurance page.