By Chris Williams on September 29, 2017.

Phorid flies, drain flies, fungus gnats, fruit flies, house flies, blow flies – can you tell them apart? Probably not, you just know that something annoying with wings has invaded your home and is driving you nuts. Fortunately, the experts at Colonial know flies and can solve your problem.

Killing individual flies will give you some temporary relief. But we know that you don’t solve a fly problem until you locate the breeding site, which means the material that the larvae, or maggots, are feeding on. With flies, that almost always means something yucky or decaying.

The first four flies listed above belong to the small fly group (all about 1/8-inch long and dark in color) and will look pretty much the same to the untrained eye. Identifying the flies causing your problem will provide clues to help find the breeding site, or sites. We call these small flies the “wet gunk gnats” since they all breed in some kind of slime, goo, or fungus. But each fly prefers a certain type of gunk:

Phorid flies – Also called humpbacked flies. Larvae feed in a wide variety of materials, including some pretty strange things such as corpses, open wounds, and mushroom farms. Common larval sites are scummy drains, dirty garbage cans, rotting vegetation, and sewer line breaks. See Phorid Flies Develop in Many Different Sites.

Drain flies – Also called moth flies because with their fuzzy wings they look like miniature moths. Common larval sites are sink, floor, and tub drains where larvae feed on the gelatinous goo that accumulates inside pipes; also dirty garbage cans and sewer leaks. See Bathroom Flies That Look Like Little Moths?

Fungus gnats – The most common larval site, by far, is overwatered house plants or indoor terrariums. Fungus gnat larvae feed on fungus and decaying vegetation in soil that is constantly wet. See Fungus Gnats Are Common Where There Are Potted Plants.

Fruit flies – Also called Drosophila flies. Larvae feed primarily in overripe fruits or vegetables and other materials that are fermenting or are vinegary or yeasty such as wine, beer, pickles, ketchup; also in dirty garbage cans, drip pans, floor drains, etc. See “Where Are These Fruit Flies Coming From?”

House flies and blow flies are considerably larger than the gunk gnats and are familiar to most people. It’s important to be able to distinguish between the two though since breeding sites for the maggots can differ.

House flies – Adult house flies are about ¼-inch long and mostly dull gray. Maggots feed in warm, moist, organic material that is decaying and often come in from outside breeding sites. The most common feeding site for house fly maggots is animal feces; others are rotting food, dirty garbage cans or dumpsters, and animal carcasses. See Sources for House Flies Inside a Home.

Blow flies – These flies are slightly larger and bulkier than house flies, often shiny or metallic in color, and make a buzzing sound. Blow fly maggots are usually associated with a decaying animal carcass; also found in animal feces or rotting vegetable matter. See Blow Flies & Carcasses.



We’re not satisfied until you are. Learn More