Fruit Flies vs. Fungus Gnats: What's the Difference?

This page is a general guide that explains the differences between fruit flies and fungus gnats. To remove fruit flies and fungus gnats in your home, follow the links in this easy-to-use DIY guide and use the recommended products for complete control.

Homeowners often assume tiny flying insects around their kitchen and home are fruit flies or fungus gnats since they are both common indoor pests. While fruit flies are commonly mistaken for fungus gnats, they are different types of pests, each with their issues.

Fungus gnats are primarily a problem for indoor house plants and other potted plants. The larvae feed on the plant's roots, limiting its ability to take up nutrients and stunting its growth. While you may not have many potted plants in your house to deem this an issue, the fungus gnat can become a nuisance due to its large population numbers and annoying hovering.

Like fungus gnats, fruit flies quickly overwhelm your house's kitchens or other indoor areas with their fast-reproducing rates. Another danger associated with this pest is any physical contact with contaminated food, which results in skin irritations or allergies for some homeowners. Regardless, learning the physical and habitat differences between fruit flies and fungus gnats in this article can better prepare any do-it-yourselfer.

Is It A Fruit Fly or Fungus Gnat

Before proceeding with a treatment approach, you must know what fruit flies and fungus gnats look like. They may look the same at a glance, but they are not the same pests. Knowing the physical differences can help you avoid using the wrong products.

For a physical reference, take a look at the image above. On the left is a fruit fly, and on the right is a fungus gnat.

Size

Fruit flies and fungus gnats measure about 1/8 of an inch in length.

Color and Body

Fruit flies are tan in color and have the round body shape of a house fly, just smaller.

Fungus gnats have a longer and narrower body shape than fruit flies. They also have large, gangly legs that resemble those of a mosquito. These pests are dark brown to black in color.

Eyes

Fruit flies are easily separated from fungus gnats by their large red eyes, whereas fungus gnats are small and compound. 

How to Know If You Have Fruit Flies or Fungus Gnats

After you have compared the physical differences between these pests, you may wonder how fruit flies or fungus gnats got into your home. Both pests can live outdoors but often travel into your home through various methods.

When fruit flies are inside, they stay near warm and wet organic areas such as the slime in sink drains and garbage disposals, fruit or vegetables sitting out on kitchen countertops or in bowls, and around rotting fruit in trashcans, which creates an ideal site for breeding and food. Fruit flies can find their way into your home through cracks and crevices around windows and doors, or they might be caused by a previous infestation or past egg-laying activities on food brought from the store or garden.

Fungus gnats are mainly found outdoors as they depend on a moist environment with decaying matter like fungi to feed on, which is often located within the soil. Damp soil in outdoor gardens and indoor potted plants are often hot activity spots for fungus gnats. Usually, fungus gnats come into your home by traveling through open doors, cracks, and crevices around the structure, or pests hatched from eggs laid in potted plants brought from the outside.

Do Fruit Flies or Fungus Gnats Bite

Though fruit flies and fungus gnats are flies, they do not bite people or animals. These pesky non-biting flies lack the mouthparts to bite or penetrate the skin.

Fruit flies will pierce fruit and vegetables by releasing catabolic fluid that helps break down their food, then use their mouthparts to suck it up or to insert their eggs. While fruit flies won't bite people, they can cause allergic reactions such as itchy, irritated red bumps on your skin, causing homeowners to think they have been bitten.

Due to their name, fungus gnats are often lumped in with other gnat pests, such as no-see-ums, which can cause tiny, red bumps that are itchy and irritating. However, as mentioned earlier, the fungus gnat is a type of small fly, not a gnat at all.

Key Takeaways

How to Get Rid of Fruit Flies

• To get rid of fruit flies, you must first sanitize your home by removing all rotten or uneaten fruit and vegetables, wiping off countertops with a rag soaked in warm water, and then sealing all exposed foods in a plastic container. Treat other breeding and food source buildup in drains, sinks, and garbage disposals with the Forid Drain Gel Cleaner. Once all food sources have been removed, set up a fruit fly trap like Natural Catch Fruit Fly Traps. Spray any fruit flies in sight with Pyrid Insecticide Aerosol.

How to Get Rid of Fungus Gnats

• To get rid of fungus gnats, address any moisture buildup in and around your home and potted plants. To avoid excessive moisture, spray indoor potted plants with a spray bottle and let enough days pass for the soil to dry. Apply fly traps like Musca-Stik around indoor potted plants, then take them outside and treat them with Supreme IT. Allow enough time for the plant to dry before bringing it back in. Lastly, directly spray Pyrid Insecticide Aerosol on fungus gnats you may see traveling in your home.

Do Fruit Flies Live in Potted Soil

• Fruit flies do not live in potted soil but are found near it due to their need to feed on rotten organic debris, such as fungi and fallen fruit or vegetables.