Apr 18, 2012 – Phorid Flies In The Homes
QUESTION:
I am dealing with a phorid fly problem in a 24 family building with underground parking. Below the units firewalls separate the building into 3 groupings with 8 families in each one, 4 up and 4 down. They are only getting the flies inside the last 8-family unit and only inside some of the apartments (3 lower and 1 upper unit). The plumbing has been scoped and no breakage or problems found and there is no smell in the units of these clean tenants. The parking area below the units where all the plumbing goes never has any problem at all and the flies pop up throughout the year every so often but not constantly. I can't find a source. Any ideas?
ANSWER:
Phorid flies exist commonly in nature, so if you were finding just a few flies now and then in these apartments, and randomly at that, it could just be flies coming from outside. But, since you are finding many of them consistently in the same few apartments it strongly suggests a source within the building and connected to these units. If the plumbing truly has been inspected by a licensed and qualified plumber and found to be in good condition (and that is probably a blessing) then some other source is present.
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I am dealing with a phorid fly problem in a 24 family building with underground parking. Below the units firewalls separate the building into 3 groupings with 8 families in each one, 4 up and 4 down. They are only getting the flies inside the last 8-family unit and only inside some of the apartments (3 lower and 1 upper unit). The plumbing has been scoped and no breakage or problems found and there is no smell in the units of these clean tenants. The parking area below the units where all the plumbing goes never has any problem at all and the flies pop up throughout the year every so often but not constantly. I can't find a source. Any ideas?
ANSWER:
Phorid flies exist commonly in nature, so if you were finding just a few flies now and then in these apartments, and randomly at that, it could just be flies coming from outside. But, since you are finding many of them consistently in the same few apartments it strongly suggests a source within the building and connected to these units. If the plumbing truly has been inspected by a licensed and qualified plumber and found to be in good condition (and that is probably a blessing) then some other source is present.
We know that phorid flies are attracted to certain conditions that provide food for their larvae, and this is not going to change. By that I mean that the larvae feed on a wide variety of decaying materials, either plant matter or even flesh. Dead animals could be fed on by the larvae, but since this is a lingering problem and you or the tenants detect no smell of decaying flesh hopefully this is not the source. Other common sources include grease traps in restaurants, filthy garbage cans, any buildup of sludge in wet areas such as low-lying areas, inside drains, within water basins of any kind, and in soils where sewage accumulates with its concentration of organic matter. They also will breed in the same kinds of resources as do vinegar flies, such as fermenting fruits and vegetables. They are found in garbage cans and anyplace where garbage may accumulate and begin to decompose. Compost piles can produce large numbers of them if not properly maintained, as could thick layers of mulch outside. Bins holding containers for recycling could produce the flies.
Virtually any place where water accumulates and remains wet can build up the organic materials that the larvae feed on - sludge, slime, fermenting materials, etc. Dry places will not support the larvae. The question obviously is what circumstance exists there that is common to these 4 units that seem to be getting the problem, but is not close enough to those other 2 separated groups of units to let the flies get into them. This can only be answered by that thorough inspection that eventually will discover the source, at which point you, hopefully, go "Ah HA! - here it is". Hopefully be offering a multitude of possible larval sources you can do another inspection, including interviewing the tenants to see which of these may exist, and be able to look in new directions.
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