How to Kill Outdoor Gnats

Written by barbara stanley
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How to Kill Outdoor Gnats
Gnats can swarm a person, seeking moisture from sweat. (Chung Sung-Jun/Getty Images News/Getty Images)

A gnat is just a common name for different types of flying insects. They can usually be found in swarms around rotting plant material and rotting mushrooms. One type of gnat, called a midge, is a carnivore. A midge will bite humans. All gnats are attracted to moisture, including human sweat. When gathering outdoors during warmer months, keep all foods covered with lids or a good sealing cling film. Keep fruit in the refrigerator inside the house, not on counters or bar tops. The ripening fruit attracts gnats, which will lay their larvae in the fruit.

Skill level:
Moderately Easy

Things you need

  • Vinegar
  • 4-quart bowl
  • Cling film
  • Ice pick
  • Hairspray
  • Fly traps
  • Several potatoes---not firm

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  1. 1

    Pour a 473ml. bottle of vinegar into a 4-quart bowl. Fill the bowl to within 2 inches of the top with cold water. Cover the bowl with cling film that seals tightly. Poke several holes in the cling film with an ice pick, keeping the holes small. Set the bowl on a table, stool, etc., nearby an outside gathering. The gnats will go inside the bowl and drown.

    How to Kill Outdoor Gnats
    Gnats can ruin a picnic. (Jupiterimages/Comstock/Getty Images)
  2. 2

    Spray any cheap hairspray into a swarm of gnats. The spray will stiffen their wings and suffocate them. This may have to be done several times to get all the gnats, as some will escape each time.

    How to Kill Outdoor Gnats
    Even humans avoid breathing the fumes of hairspray. (BananaStock/BananaStock/Getty Images)
  3. 3

    Hang sticky fly traps around the outdoor area. You may also make your own fly traps by cutting a brown paper bag into strips 3 inches by 8 inches. Use a hole punch to make a hole at the top of each one. Thread a ribbon or piece of string through the hole and tie it off to make a hanger. Dip the strips into a mixture of 1 cup corn syrup and 1/4 cup cane sugar. Place the strips on a tray to take outside. Hang your flytraps around the outer perimeter of your gathering.

    How to Kill Outdoor Gnats
    Store-bought or homemade flypaper attracts flies, gnats and mosquitoes. (Stockbyte/Stockbyte/Getty Images)
  4. 4

    Spray your body and clothing with a spray that contains 15 per cent to 25 per cent DEET. This will keep gnats away. Herbal remedies include a strong mint spray. Soak 0.227kg. of fresh mint or 0.113kg. dried mint---such as peppermint, spearmint, or lemon mint---in enough rubbing alcohol to cover the plant material. After soaking for three or four days, strain the plant material and retain the liquid. Add 1/2 cup of lemon juice to the mint liquid. Mix it well, then pour it into spray bottles. Spray your body before going outside.

    How to Kill Outdoor Gnats
    Some people are allergic to insect sprays. (Jupiterimages/liquidlibrary/Getty Images)
  5. 5

    Cut up old potatoes into four pieces each. Place several pieces of potato in shallow containers---lids will do---and put the containers in four or more places where gnats have been seen. Gnats will go to the potatoes to lay their larvae. At the end of the evening, gather all potato pieces and toss them into the campfire. Alternatively, place them in a paper bag and spray DEET into the bag, then dispose of the bag. This will prevent larvae from hatching, according to "How to Kill Gnats: Essential Tips on How to Kill Gnats."

    How to Kill Outdoor Gnats
    Children can cut the potatoes with adult supervision. (Seiya Kawamoto/Lifesize/Getty Images)

Tips and warnings

  • Use dish detergent in water if vinegar is not available.
  • Set out a bowl of vinegar and water near you as you garden.
  • Sprinkle baking soda over your compost bin where gnats lay their larvae and feed on the rotting plant material.
  • Give any children present a bottle of soap bubbles. As they blow the soap bubbles, gnats will stay away.
  • Never spray your face or the face of another person with insect spray. Instead, spray onto balls of cotton and use the cotton to dab the spray onto your face. As soon as you return to the inside, shower to remove the insect spray. This is especially important for children.

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