Potent Sprays & More For Fighting Gnats

Fungus gnats are small dark flies (about 1/8″ in size) that look similar to mosquitoes and are often confused with fruit flies. They thrive in humid environments and breed in the damp soil of potted plants.

Sticky TrapThe larvae is what causes damage by eating the roots, root hairs and stems. The symptoms of an infestation can be stunted plant growth, wilting, yellowing leaves and rotting roots.

The adults feed on fungi at the top of the soil (where they lay their eggs) while the larva feasts on the roots.

Here is a collection of remedies to get them out of your house along with some tips for trying to control them:

  • Dry Them Out: Allow the soil to dry very well to the point that your plants start to wither before watering again (approximately the top one to two inches of soil is completely dry). It needs to get this dry so the larvae in the soil will dry up completely (ending their cycle), the adults cannot breed in the dry soil so the cycle ends.
  • Sticky Traps: You can purchase yellow sticky cards for houseplants with the purpose of indoor insect control, these will work with fungus gnats. The idea is that the color yellow will attract them and when they come to investigate, they will be stuck or trapped by the sticky substance on the card. Look for these in home and garden centers or greenhouse supply stores. If you’d like to try making your own, cover bright yellow index cards with Vaseline or Honey. Tape the card to a straw or chopstick and stick into the soil. Another easy sticky recipe is to mix equal parts petroleum jelly and liquid dish soap then use the goop to cover the yellow card.
  • Killer Soap Spray Recipe: Mix 2 tablespoons Ivory liquid soap or lemon dish detergent with 1 gallon of water, use this mixture to water and drench the soil that is hosting them. After about an hour, lightly spray the leaves with clear water to rinse the soap off.
  • DIY Trap: Pour a tablespoon or two of apple cider vinegar into a small cup, top with water. Leave the cup near the plant with the problem. They will be attracted to the vinegar and will be killed by drowning.
  • Vodka Spray: Mix 1/2 cup vodka with 1 1/2 cups water, pour into spray bottle. Spray (first test a leaf to make sure the alcohol isn’t too harsh for it, if it doesn’t burn the leaf after a day or two it should be fine).
  • Rubbing Alcohol Spray: Mix 1 cup rubbing alcohol with 1 quart of water, pour into spray bottle. Spray and treat every three days for two weeks. Make sure to test a leaf first to check the mix isn’t too harsh for it.
  • Tobacco: Break open a few cigarettes and make a light layer of tobacco over the top of the soil, the nicotine will repel them. Do not use on herbs or plants that are eaten and watch that pets don’t have access to the tobacco.


  • Try putting a layer of sand on top of the soil, this may help deter the little pests from setting up home.
  • How to tell if a plant has the little critters? Here’s a trick to find out if you’re not sure: slice a chunk of raw potato and leave it on top of the soil where you suspect they are thriving (lay it cut side down). After seven days, lift the potato up–if you have them you will see larvae on the potato.
  • To prevent another infestation, reduce watering as gnats are usually a sign of over watering. Also make sure to remove any water from the saucer underneath the pot. Make sure soil is dry between waterings.
  • Remove fallen leaves and plant debris so there’s no organic matter resting on the soil to attract them to feed on.

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What Readers Are Saying: 39 Comments
  1. Chris says:

    It is so refreshing to actually type in the request in Google, get the results and then click on the webite that will give you the answer to your questions! Congratulations, you win– I get so tired of having to search each website trying to find the answer by going through several hunreds of answers to see where your answer exists—yours went right to the problem and answer–GOOD JOB!

  2. Michael says:

    everythjing sounds great!! πŸ™‚

    does the”gnat killer soap spray” also kill the larvae???

  3. Barb says:

    If you place a few mothballs in the water before sprinkling your plants, you will never have gnats. I like to keep an old juice bottle for this. Place some mothballs in an old stocking (they will float in the water, this keeps them from coming out with the water), fill the bottle w/the mothball stocking in it with water….use it whenever you water your houseplants.

    • Mala says:

      Can you let me know how many mothballs to how much of water ?
      I have a 10 inch planter with a house plant that is infested.
      Any help is appreciated.
      Thanks !

      • Kyle Kissmann says:

        Not sure when you posted inquiring about mothballs but this is not a guaranteed method. I have indoor banana trees. Had a bad infestation last year. Put mothballs in the planters because another site suggested that would deter and kill the gnats, it did none of this. even with water mixed with the mothballs. They continued to flourish and the house smelled like old folks. I’m on this site now, plan to try some of the other methods if I get a problem with them this year.

        What I did find somewhat effective if it gets real bad is, especially in the winter, take the pot outside, thoroughly wash as much dirt out of the rootball as possible, clean the planter with soap and water, and then replant the tree, bush, flowers, whatever in the planter with fresh soil. This year I’ve devised a pvc system to get the water below the soil since I’ve upgraded the size of my planters and this size doesn’t have the self watering place at the bottom. I have liquid soap, fly traps, and rubbing alcohol at the ready, but I may have to try that yellow card and Vaseline suggestion. I also covered the top of my planters with duct tape, hoping that will keep dead plant matter out of the planters and will stick any bugs that do get into the planter itself.

    • Sandra says:

      Mothballs are poison, dangerous for kids and pets, Can Kill, Should be avoided . Please try something less lethal.

    • Tenos says:

      Mothballs are highly poisonous; They’re literally referred to as “the old lady poison” (and other more creative nicknames) in homicides, they are extremely lethal, which is why many people use alternative methods of repelling insects now a days, rather than mothballs. …If you were to ingest just a small amount of that mothball saturated water, you would die. You should be careful with such an unnecessarily dangerous method.

  4. Diane E says:

    Are these the same as the ones flying around near lakes? We live by a lake and this summner we have been bombarded by tons of gnats flying around near our dock where my husband keeps his boat. We don’t have any plants near the dock? Thanks for any help!!

  5. Brigitte says:

    I discovered a new trick by fluke! I was soaking some clothes in OxiClean and when I came back a few hours later, the sink was full of drowned gnats!! I left the water there for a couple days and tada!!! They’re all gone! πŸ™‚

  6. Patti says:

    I find this site very informative…I am trying to figure how to get rid of mushrooms in my yard..something that will not harem my grass. Any ideas?

    • Nici says:

      I had a terrible mushroom problem in my yard, I poured Dawn dish soap all over my yard and then used the garden hose and sprayed my yard. It was a big pile of bubbles all over so it was kinda fun but it worked!! A week later they were all completely gone πŸ™‚

  7. Michelle says:

    We don’t have any plants in the house and no fruit, but we keep getting all these stupid gnats. What would you suggest I use to get rid of these irritating bugs?

    • traci says:

      Its only spring time were getting a gnat problem already. I don’t have plants or fruit in my house. These gnats seem to be coming from my drain. I have poured drain cleaners down the sinks bit still no luck. Does anyone have a solution for these pest?

      • Mbb says:

        I have had these sewer gnats before. The best thing to do is to pouur bleach down your drains at night and they will eventually quit hatching out.

      • cutter says:

        Traci & Michelle,
        You probably have drain fly’s. Pour some backing soda down your drains followed by some white vinegar. Then put the drain cover on. After a short time pour some boiling water down each drain. That should take care of it & as a bonus your drains will be really clean.

  8. Janet says:

    I had fungus gnats in my plants……putting peroxide in the water did the trick….took awhile but it did work….

  9. Judiuni says:

    I buy cloves from the supermarket’s spice section and put them in the pots of my house plants to repel gnats. It doesn’t kill the adults but stops them from breeding and they’ll all soon be gone. You have to put new one in about every (other) year. This has worked for me for many years.

  10. laurie says:

    Mothballs are poisonous and stink! Personally I like the other methods better so my house won’t smell

  11. Terah says:

    We are bombarded w/gnats in the yard, you can’t walk w/o stirring them up, have acreage and it’s awful…..any suggestions for getting rid of them in the grass?

  12. Crystal says:

    I’m going to try the apple cider mixture. I’ll try it for the backyard gnats. I’ll let you know how it works.

  13. Julie says:

    We do not have plants in the House but the gnats are awful in the bathroom? What can we do for that? We have tried the apple cider vinegar but it isn’t working either! Any suggestions?

  14. Ron says:

    PLEASE, does anyone know how to get rid of biting Florida Sand Gnats??

  15. Linny Jorde says:

    My houseplants are all outside for the summer except for a few trees but instead of the usual diminishing of the quantity of these little beasts, they have exploded this year and are crawling and flying everywhere. I’ve got sand and something else – Bt? to put into the plant’s water (just got it) and a soap spray to spray on the leaves but I need to get rid of the flying ones. But there is a big BUT. I have cats and even many natural sprays with essential oils like peppermint, windergreen, etc. can be harmful or deadly to cats even through inhalation. What can I do before we all go nuts? YES, I am catching them on sticky paper. I am leaving cups of water and cider vinegar and yes they fling themselves into it, but they are still all over the walls and floors and flying in the air. Help!

  16. brenda says:

    have nats flying alot in my house we have no plants trying to find some kind of spray to spry and kill them help me please somebody

  17. Diana says:

    We get these gnats all summer. Never dilute the apple cider vinegar, and just use it full strength.. I put it in a cup and change it out when it gets full. Keeps the gnats down all summer.

  18. Johann says:

    It’s nice to see a use for that Vodka I’ve had sitting around my house for a couple of years. I always joke that alcohol is a toxin, glad it’s a bug toxin too!

  19. Wm says:

    I have a problem with knats here in Abilene, TX. I tried various methods to get rid of them. The most effective was to put apple cider vinegar with a very few drops of liquid detergent. in 4 small glass vases ($2 each at Dollar General) and place a paper cone with a 1 to 2 inch opening at the bottom that site just above the cider. The top of the cone is made wide enough to rest on the opening of the vase. A plain glass can be used also. I wanted something a bit larger. The first time I tried this, I made two of them and from between 12 noon the first day until 6 PM the next, I trapped and drown 68 knats total. This method works very well. The other think method I used was to mix 5 cups of water with 1 cup of bleach and pour that down the kitchen and bathroom drain every evening, sealing the drain with a plug. This system takes about a week to rid all but an occasional knat from time to time. I stopped treating and put up the traps too early this year and the infestation returned.
    There is one other interesting way I have discovered to trap knats. Whenever I eat something in a bowl in the evening and then put lemon scented liquid detergent in the bowl, fill it with water, and leave it in the sink to finally wash later, the knats will be attracted to the smell of the food and fly into the dome of detergent bubbles, getting trapped. This happened last night and I found about 12 knats therein after only a couple of hours. You might have to squish the knats with your fingers to make sure that they are dead. I am going to buy can of $1 lemon shaving cream and try putting a layer on top of some apple cider vinegar later.

  20. Cheryl says:

    I have had fruit flies in the past in house plants, both black and brown and have successfully gotten rid of them with apple cider vinegar and yellow sticky paper. I recently discovered I have gnats which are not interested in the Apple cider vinegar at all.I am using yellow sticky paper & have not watered my plants for three weeks plus, and am still seeing Gnats!!! Thought I would try using tobacco and cloves, am assuming you use the whole clove. How has other people’s success been with these remedies?

  21. Cheryl says:

    Anything liquid to put in soil to kill larvae?

  22. Dawn says:

    I have house plants but the gnats are in my bathroom. Sometimes in my kitchen I use a shot glass pour some white vinegar and a few drops of Dawn dish soap. But every few months they always come back how do I kill them for good and how do they reproduce in the the bathroom

  23. tina zugg says:

    I have a good tip for killing those nats diatomaceous earth (food grade) its a bug killer u can eat.

  24. Pat says:

    I read on Pinterest about using cinnamon. I sprinkled a heavy layer on top and quit watering.It’s been about 10 days now and no more gnats am repotting in new pot and soil.

  25. Angel says:

    I have a rhipsalis burchellii and it just started to grow really fast and now it has the little gnats and the leafs are not falling off or getting yellow. I think the plant started to grow more because i water it more often but now i have gnats. I have to go back to watering it one time in two weeks.

  26. Lynn says:

    Is there a solution for killing gnats with an indoor herb garden. Like will the sticky cards effect the herbs since the herbs will be used in cooking?

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