Phorid-Humpbacked Flies

Facts, Identification & Control

Latin Name

Family Phoridae


Most are black or dull brown, but some are yellowish in color. Very small—0.5 to 5.5 mm. The arched thorax of the adult gives them a humpbacked appearance.

Behavior, Diet & 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.”

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


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.

Signs of a Phorid Fly Infestation

The most apparent sign of phorid flies is the adult flies. They often are observed buzzing around rooms and scurrying across counters or other surfaces.

More Information

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 0.5 to 5.5 mm 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.

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 Certain species of phorid flies are used as biological control agents of fire ant.

Life Cycle

Like most flies, the phorid fly undergoes a complete four-phase life cycle including egg, larval, pupal and adult stages. Depending on species, temperatures and the hospitality of the environment, the phorid fly spends 11 to 22 or more days to become adults.


These flies are difficult for homeowners to completely control with any pesticides. 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).