[Annual Fly Control Issue] What do phorid flies cost?

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Measuring only 1/8 inch or less, phorid flies are sometimes confused with fungus gnats and fruit flies. These flies may be small, but getting rid of them could require tearing open walls, ripping up floors and inspecting the insides of plumbing lines, leading to soaring costs and a lot of inconvenience for facilities.

Like many other flies, phorids breed in and feed on most decaying organic matter. But Copesan Technical Committee members find that, more often than not, phorid flies select waste plumbing leaks as their preferred breeding sites. Phorids represent a serious health threat when they fly from putrid decaying matter onto clean, sterile surfaces and foods. As with all fly problems, the primary solution to eliminating phorid flies is not chemically based, but relies more on housekeeping and correcting plumbing problems. Using only pesticide applications without fixing the underlying reason that the flies are present will result in frequent chemical applications and a revolving door of different pest management firms trying to fix the problem by only treating the symptom.

BIG PROBLEMS. The following case studies describe the measures that may be necessary to fix a phorid fly problem and the costs associated with them. The costs could amount to tens of thousands of dollars, as well as an interruption in business, which could be as costly as the repairs, if not more.

Surgical intensive care recovery room. Waltham Services, a Copesan Partner in the Northeast, worked with a major Boston-area hospital that was forced to take a surgical intensive care recovery room out of service and seal it off because adult phorids were spreading throughout the intensive care recovery suite. Opening a wall revealed a plumbing leak and a cloud of flies.

Hospital kitchen. In another case, tearing up a small floor section in a suburban hospital kitchen revealed leaking pipes and a muddy organic accumulation in the soil beneath the floor slab, the perfect site for breeding phorid flies.

Nursing home. A Connecticut-based nursing home had a phorid fly problem so bad that the flies were leaving the basement area and spreading throughout the facility into patient rooms. Elderly patients sleeping with their mouths open were being found with flies on them. The nursing home kitchen had to be disassembled and moved to the dining room space, and the entire floor needed to be ripped up. Opening the ground beneath the kitchen floor revealed multiple old cast iron pipes that had been leaking organic matter into the soil for years. There were hundreds of empty fly pupal cases per square inch of soil. The cost to temporarily relocate the kitchen, jackhammer the floor, fix the broken pipes, remove contaminated soil and replace the kitchen was reported in the $25,000 to $30,000 range.

Facility grease traps. In Illinois, McCloud Services, a Copesan Partner serving the Midwest, had two instances with clients where grease traps were responsible for the phorid fly infestations.

In one situation, the phorids were breeding in the soil of a crawlspace. The grease trap in this facility had leaked and contaminated the soil underneath the kitchen. The contaminated crawlspace soil needed to be removed at a total cost of $10,000.

In the other situation, phorid flies were getting into a hospital operating room, and grease traps were once again the culprit source. The hospital had a large internal grease trap in the basement. Phorid flies were breeding inside the grease trap and escaping through tiny gaps in the grease trap lid. Periodically, the trap was opened for pumping. Large numbers of flies escaped during the pumping operations and quickly spread to various areas of the facility. The solution in this facility was to reroute the plumbing to an exterior grease trap, and it cost $500.

Contaminated soil. Another Copesan Partner from the Midwest had a client with a contaminated soil situation that ended up costing $75,000 in removal and repairs. One common thread in these instances is that most of these facilities are 50 to 75 years old or more, and the fly problems appeared in an older part of the facility. Older facilities are especially at risk because cast iron plumbing becomes brittle with age and often will crack or break open, allowing leaks when floors, walls and buildings shift ever so slightly and exert pressure on the pipes.

BEYOND A BAND-AID. All types of facilities are at risk of having major phorid fly problems. So what steps should you take if you suspect a problem at your customer’s facility? Inspection and proper identification. All fly control begins with the inspection and proper identification of the species involved. The thorough inspection process involves client feedback. Client reports of leaking drains, pipes, backed-up sinks and off odors often can lead directly to the source of problem.

Leaking pipes and drains allow organic material to accumulate in the soil beneath cement slabs. The ground becomes so enriched with organic material that the ground becomes the ideal breeding medium for flies. Finding, caulking and sealing these tiny cracks and openings may provide temporary relief, but ultimately the damaged pipes must be repaired or replaced and the contaminated soil removed and replaced with clean material, if necessary.

Getting access to the source of the leaks many times requires tearing open walls, ripping up floors and inspecting the insides of plumbing lines with a camera. Drilling pilot holes in floors and opening small wall sections to look for leaks and odors should be done first before the more invasive steps of removing entire floors and walls for repair. With a good inspection, a curious, questioning mind, and cooperation between pest management professionals and facility management, phorid fly problems can be eliminated.

Berman is technical director, Waltham Services, Waltham, Mass., and Hottel is technical director, McCloud Services, Hoffman Estates, Ill.