Phorid-Humpbacked Fly:  Facts, Identification & Control

Latin Name:

Family Phoridae

Appearance:

Most are black or dull brown, but some are yellowish in color. Very small—1/16- to 1/8-inch. The arched thorax of the adult gives them a humpbacked appearance.

Habit:

Characteristically short and erratic flight. Adults have a peculiar habit of rapidly running across windows, TV screens, tables, walls and plant foliage. These flies are frequently mistaken for “gnats.”

Diet:

Some species feed on fungi, while others are parasites of various insects.

Reproduction:

Larvae develop in moist areas where organic material and standing water are present. Phorid larvae also develop in animal matter. The entire life cycle lasts 25 days or more, depending on the environmental conditions and the availability of food.

Phorid Fly Facts:

Phorid flies are also known as “sewer flies.” To the naked eye, phorid flies resemble common fruit flies in appearance, with bodies measuring less than one millimeter in length. Phorid flies are often called “humpbacked flies”. They are characterized by their humped thoraxes. Body coloration ranges from black to brown to yellow. They are found all over the world, but favor warm, tropical regions. Although they are commonly mistaken for gnats and fruit flies, phorid flies have more in common with filth flies, such as the common housefly.

The phorid fly is also known regionally as the scuttle and coffin fly because it favors decaying, moist organic material as both a source of food and a prime site for laying eggs. They are also fond of decaying flesh and are known to favor dead animals over rotting vegetable matter. Phorid flies are capable of creating sustainable communities in coffins and are therefore of interest to the forensic community, which is discovering new evidence examining coffin flies. Phorid flies are also under examination as possible fire ant controllers in the South.

Life Cycle:

Like most flies, the phorid fly undergoes a complete four-phase life cycle including egg, larval, pupal and adult stages. Depending on temperatures and the hospitality of the environment, the phorid fly spends between 14 and 37 days in its larval and pupal forms.

Control:

These flies are difficult to control with any chemicals. The situation has to be assessed and the source of the infestation determined. Is it a clogged drain or a broken pipe? Is it a clogged sewer line or a broken sewer line? In many cases the floor must be removed and the pipe repaired; and the soil around the break has to be removed. Applying chemicals in the pipe will rarely work. The best solution to this problem is to first, physically clean the drains–remove as much of the organic material as possible; then use a biological drain cleaner on a regular basis (every two weeks).