When you're constantly shooing tiny flies away, you're probably not looking too closely at them. You might even find yourself dismissing them as either fruit flies or gnats, not caring which they are. While fruit flies and gnats are both tiny pests that irk a lot of people, they're completely different creatures.
Fruit Fly and Gnat Families
Although fruit flies and gnats are both small flying insects, they're from different families. The common fruit fly (Drosophila melanogaster) is in the Drosophilidae family, while gnats come from different families, including Sciaridae, Anisopodidae and Mycetophilidae, and there are many gnat species.
Finding Fruit Flies
Fruit flies are the ones you're likely to see in the kitchen. They gravitate to warm and wet areas without much air flow. As the name implies, they invade vegetables and fruits in kitchens. Although fruit flies can appear at any time of year, they're particularly prevalent at the end of the summer and in fall. They're drawn to mature produce.
If little flying insects are making you throw your arms up in exasperation outdoors, there's a strong chance you're dealing with gnats, rather than fruit flies. Gnats are generally seen outside. Fungus gnats, for example, are typical sights in moist soil outdoors. They also spend a lot of time in rotting organic matter, so you might see them near your compost pile. Fungus gnats once in a while find themselves indoors, and they may breed there. Eye gnats, like fungus gnats, live outdoors.
Clear Physical Differences
Although you'll likely never get a close look at a gnat or fruit fly that's annoying you, they don't all look exactly the same. Mature fruit flies are generally beige or brownish-orange, roughly 1/8 inch long. They typically have red eyes. Eye gnats are usually glossy and black and around 1/16 inch long. Fungus gnats are generally deep gray or black. When they're adults, they usually reach roughly 1/8 inch long.
- Homegrown Sprouts; Rita Galchus
- University of Kentucky Entomology: Fruit Flies
- Iowa State University Extension: Don't Make a Home for Fruit Flies
- Iowa State University Extension: Gnats That Drive You Nuts
- Colorado State University Extension: Flies in the Home
- Oklahoma State University Entomology & Plant Pathology: Fruit Flies
- University of California Statewide Integrated Pest Management Program: Eye Gnats
- University of Vermont Extension: Fungus Gnats
- County of San Diego: Eye Gnats
- County of San Diego: Eye Gnats in San Diego County
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