How to Get Rid of Gnats or Fruit Flies

Although fruit flies are sometimes casually dubbed "gnats" -- particularly "banana gnats" or "fruit gnats" -- this is actually a case of mistaken identity. While the pests come from the same family, they infest living spaces differently and call for different treatment methods. Sticky traps and pesticides treat gnats, while do-it-yourself solutions and plenty of thorough housecleaning target fruit flies.

While brown fruit flies measure about 3 millimeters in length, smaller gnats -- typically fungus gnats, in the case of indoor infestations -- clock in at an even tinier size of about 1 millimeter and feature a darker black shade than fruit flies. Gnats tend to float in a cloudlike formation, while fruit flies buzz and dart around their nesting grounds. Both types of insects enjoy moisture and humid organic matter: fruit flies are attracted to rotting or over-ripe produce, fermented liquids and unclean trash bins, while gnats are particularly drawn to moist soil that contains fungus. This makes the gnats far more likely to appear in compost bins, gardening soil or on houseplants than their larger cousins.

Excess moisture in houseplants encourages fungus gnat infestations, so avoid over watering to prevent gnats from appearing. Use pots with good drainage and trim your plants of decaying vegetation to help them stay gnat-free. Fungus gnats often arrive in potting soil. You can buy pasteurized soil, or heat-treat it before potting by putting it in a black plastic bag in a sunny location for about 4 to 6 weeks. Once they attack your plants, trash or soil, you can trap adult fungus gnats with the adhesive sticky traps commonly available at home and garden centers. Similarly, raw potato chunks bait and trap gnat larvae, which live exclusively in soil, but this method is not recommended for homes where residents are also dealing with fruit fly infestations. Bacillus thuringiensus, or Bt, solution also does the trick. Make sure the Bt subspecies you get is labeled for fungus gnats, as different types target different insect populations.

Fruit flies most commonly get to your kitchen as eggs or larvae on fresh fruits and vegetables. Prevent fruit flies from ever showing up by washing and refrigerating produce as soon as you bring it home. Fruit flies are sensitive to cold. Once you have an infestation, a multi-pronged attack will get rid of it within a few days. First, identify breeding grounds, typically sweet liquid spills, stinky trash bins or recycling receptacles, dank spaces, or most commonly, ripe produce in the fruit basket. Wash and refrigerate -- or dispose of -- produce that was left out, then clean and dry the surrounding space with soap and water. Optionally, use jars baited with apple cider vinegar, wine or rotted fruit, with paper or plastic funnels over the jar's mouth, to bait and trap the adult insects. However, adults will die off naturally within a few days, so if you just make sure they have have no place to lay eggs, you will have won the war handily.

While soap and water or a spray of plain alcohol are just as effective for killing soft-bodied insects as prepared insecticides, gnats and fruit flies are both also susceptible to pyrethrum aerosol. If you turn to this solution, always read and follow any manufacturer-provided warnings or instructions. Pyrethrum spray can float in the air for some time after it's used, which is why it is effective for flying insects. It moves around on air currents, where it can irritate sinuses and asthma and may settle on food and food prep surfaces. Store all food safely away from pesticides and clear the area of any utensils or food storage bins before applying.