No solutions yet for phorid fly invasions

NEW GARDEN >> For the residents of Harrogate development, the biblical prophecies of locust swarms have nothing on them.

For these homeowners and many like them in various areas of southern Chester County, the tiny phorid flies that come in warm weather and swarm in their houses are making life almost unbearable.

The time frame of the problem is recent. This has been happening since around 2011, a few years after the insecticide Diazinon was banned.

The residents gathered on Friday at the New Garden municipal building for yet another meeting to find out how things are going in the fight, and overall they were not entirely satisfied.


The tiny bugs are about an eighth of an inch in size, so they can slip into even the tiniest openings in houses. And when they do, they arrive by the thousands, coating the walls, swarming around lights and landing on anything that is moist.

According to reports by residents, the bugs have not only left them feeling creepy, but have also brought down their real estate values.

The source of these pests, they agree on, is largely documented to be in mushroom houses.

The parent bugs lay their eggs in the compost used to grow mushrooms, and the larva emerge as hungry eaters of the mycelium — the weblike root system of what is destined to produce the fruiting of the fungus. Then they take off to mate and annoy humans.

The result is that not only are homeowners frustrated, but the mushroom growers are as well, because their crop production is suffering.

On hand at the roundtable discussion organized by New Garden Township Manager Tony Scheivert, about 30 people from as far away as Upper Oxford joined to share stories and find out if any progress has been made in the fight.

The stories were similar and sometimes bordered on horrifying.

Colin Carson of Harrogate, which is just off Route 7 south of Route 41, said he can see the swarms coming. There may be a respite in cold weather and springtime, but when July comes, they arrive in increasing numbers until the first frost.

The conditions are so bad, he said, that there are instances of people trying to sell their houses and they have to reduce the price by $100,000.

Dennis Lafferty of Chatham Chase in London Grove, said the bugs like moist places, so they end up sharing the bathroom with the homeowners. How they can get there in what seems to be a well-sealed environment is still puzzling.

Lisa Sherward of Richards Run in Kennett Township said she cannot find anything to rid her home of the phorids.

And Nancy Hicks of Upper Oxford Township said they hang around food. “They taste awful,” she said, not to mention that they smell bad when you crush them.

Two voices of expertise were on hand: Kaolin Mushroom Company Director of Research and Development Eric Toedter and Penn State Entomologist Nina Jenkins. Between them, there is very little they don’t know about the growth, development, habitats and mating behaviors of the flies. The only thing they don’t know is how to wipe them out.

They reported on their work and added that one of the frustrating facts about phorid flies is that the bugs are mysterious in their decisions on where to swarm and settle. One house has them, and the next door neighbors do not.

“There are no common denominators,” Jenkins said.

“It’s baffling,” Toedter said.

Also on hand for the analysis of the management problem on the governmental side were Scheivert, state Rep. Eric Roe, R-158, and state Rep. John Lawrence, R-13.

They reported good news and bad news.

The good is that state money has been allocated to Penn State for more research. Additionally, research is ongoing.

Currently, scientists are looking at pheromones (or subtle attractive smells) that may be present in phorid destinations.

The bad news is that the mushroom industry is such a small financial segment of the nation or even the state, that developers of insecticides and benefactors of research funds are going to spend more and be more aggressive against problems of other crops and diseases. Another relatively frustrating piece of information is that Diazinon is not likely to return to use.

For now the attendees left the discussion, still sharing stories and frustration. On the good side, if there is one, they agreed that the coming colder weather will probably decrease the numbers of the creepy invaders.

About the Author

Chris Barber

Chris Barber is the editor of the Avon Grove Sun. She was previously southern bureau chief of the Daily Local News and editor of the Kennett Paper, earning honors in writing and photography. Reach the author at .