Phorids or humpbacked flies are about the same size as fruit flies or a little smaller. They are dark brown and have a humpbacked appearance – a visual effect caused by a small head located low on the front bulge of the thorax.
Wing venation consists of several short, thickened veins on the fore margin of the wing near the attachment to the thorax. These veins do not extend to wing tip, and other veins are weak or nearly invisible. Phorids run in short jerks. These flies become problems when they infest decomposing plant or animal matter. Buried animals, garbage, or broken sewer lines support large numbers of phorids. Phorids also infest bodies in mausoleums.
Adults are able to emerge from the underground infestation site upwards through several feet of soil. If broken sewer lines are under buildings, phorids can come up through cracks in concrete floors or around floor drains. When water and sewage wash out cavities in the soil around the pipe, immense numbers of flies are produced.
Carefully identify the infesting fly as a phorid. Locate the area where most flies appear. Ask clients if there have been sewer problems, buried garbage, decaying vegetable, or animal matter close by.
- Remove decaying matter and soil contaminated by it.
- Where sewer lines must be repaired, insist that sewage contaminated soil also be removed.
- Caulk all floor and wall cracks where flies may enter. Moth flies are about 0.3 cm (1/8 inch) long. Their dark colour comes from tiny hairs that cover the wings which are held inroof-like fashion over the body. Moth flies have long, drooping antennae.
- Larvae live in the gelatinous material in sink drains traps and sewers. Where sinks regularly overflow, these flies build up in the overflow pipe. When drain traps of sink, commodes, and floor drains dry out, large numbers can enter dwellings from the sewer.
- Drain traps should be cleaned mechanically with drain cleaners. Without larval control, adults will continuously emerge.
- In sewage treatment plants, drain flies feed on the gelatinous material that collects on stones in trickling filter beds. Overtime, however, cast skins from these filter flies can slow down water drainage. When sewage treatment plant filter beds malfunction or become “out of balance”, the moth flies can become problems in nearby neighbourhoods.
The filter bed should be cleaned by reverse or back flushing. It is important to understand that domestic insects carry diseases and are responsible for Millions of deaths each year because of their disease vectoring ability, particularly in less Developed countries. In urban areas flies contaminate food and people in restaurants, hospitals, and homes. They are annoying indicators of sanitation, structural, and cultural problems.