House plants causing flies

Lea Grossman
by Lea Grossman
I have a few houseplants on my kitchen window sill, and they seem to be causing a fly problem (argh). Any advice on how to get rid of them? Any ideas would be helpful
  16 answers
  • Sandi Gallion Hodge Sandi Gallion Hodge on Aug 04, 2014
    For me, it was the soil. I used older potting soil. I bought new and replanted, they were gone.
  • Katrina Katrina on Aug 04, 2014
    Its the soil had same issue an had gotten rid of it an the flies left as well good luck hope this help
  • Jeanette S Jeanette S on Aug 04, 2014
    I have gotten rid of my "fruit flies" by putting red wine vinegar and a few drops of dishwashing liquid in small containers and sitting them in my windows. Some people call these "sewer flies" because they say they come up out of the disposal and drains! They have been extremely bothersome this year! (I did a recent post on this...with photo showing flies being drawn to it).
  • Lynn Hutchison Lynn Hutchison on Aug 04, 2014
    Fungus gnats are small black flies (fruit fly size)that buzz around your plants and are generally more a nuisance of indoor plantsthan they are a problem. - Insevere infestations, the larva can damage tender feeder roots (they're in thesoil mostly eating soil algae but can snack on small roots as well).Controlling Fungus Gnats There are several ways to control this pest on indoorplants. Note you rarely see this problem in the garden as natural predatorscontrol this pest outdoors. The first is to understand the main problem is alot of soil algae as a food source and the main culprit here is overwatering.Too much water produces algae and this feeds the pest. Water well and thenallow the pot to dry down between waterings. This will be your long term methodof controlling them. However, in the short term you have a bunch of tiny,annoying black flies buzzing about - ControllingAdults You can spray the adults with insecticidal soap. Spray underleaves as well as tops for best control. You can hang sticky yellow cardsaround the plant - these are available from garden shops and this pest lovesthese cards. You'll collect a lot of them. Controlling the adults willeventually kill off the larva. ControllingLarva For the larval forms of fungus gnats, you can heavily spray thesurface of the pot with insecticidal soap. This drench will kill off the larvalforms. You can put a half inch layer of sand on top of the soil in the pot.This will tend to dry out quickly and the fungus gnats will not survive in thisdried out top layer. Once they are controlled, you can remove the sand. - This was obtain from Doug Green's gardening advise.
  • Ev Hobel Ev Hobel on Jan 15, 2015
    Fungus gnats - tiny flies that lay eggs in the soil of houseplants ruined my tomato crop last year. Yuk. They don't bite or anything. But their larva eat the roots of the plants killing or damaging them. I get it in new potting soil too. The suggestions I've tried so far are putting fungus gnat powder in the soil - mixing it in. Then a 1/4" or more of sand on top so that the sand is dry and the gnats wont lay their eggs. There are more suggestions on my pintrest if you want to go there. I forget it now. Good luck. I need it too.
    • Joy.schottenloher Joy.schottenloher on Feb 26, 2015
      You drive a motorcycle and you love to plant. Woman after my own heart. I love to LOOK at the cycles now to old to ride. Lol I don't have my own place to plant things, but I do have an amazing rose bush my husband bought me for Mother's Day. Stay safe.
  • Pamela Kolleas-Hilliard Pamela Kolleas-Hilliard on Jan 19, 2015
    Me too, I took the soil out to the garbage, then I wash the roots gently in tepid water and replanted them, they didn't show any stress and are still doing well 3 years later.
  • Joy.schottenloher Joy.schottenloher on Feb 26, 2015
    Question?...I tried to plant here.And here is San Antonio Texas. But the soil in our yard is like rocks. What can I add to keep it soft. I watch these garden shows and their soil is easily used. You almost need a drill to make a hole in mine. Any suggestions for this old lady.
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    • Grandmasue10 Grandmasue10 on Sep 22, 2015
      @Joy.schottenloher On those TV shows they have helpers who Rototill the soil and they add plenty of potting soil from the big box stores.
  • Ev Hobel Ev Hobel on Feb 27, 2015
    I did a lot of research on pintrest and I found my answers. First I put the sticky yellow fungus gnat catchers in the area where my plants were. Boy did I catch a lot. SECOND, I bought new indoor potting soil - talked with the garden experts in the garden shop. The soil was to have NO COMPOST like material (no bark, etc) since that is what the larva feed on. I'm slowly repotting my fairy gardens and keeping the new ones in a different area. Also, when I take a plant out of the old pot, I take most soil off and replant it temporarily in good soil mixed with fungus gnat powder. And just by the way, that is a 4 wheel ATV I was riding while visiting my cousin. Can't wait to get back there and go for trail rides. I'm 72 yrs. young and I'm having more fun than in years. ♥
    • Grandmasue10 Grandmasue10 on Sep 22, 2015
      @Ev Hobel Another tip: Don't take your plants outside. The only time i have a gnat problem is when I try to be nice and give my indoor plants some fresh air and a little sun. Direct sun is too strong for them and they pick up bugs. PS 73, widowed years ago and loving life just like you do.
  • Billie Billie on Aug 18, 2015
    Change the soil in all your indoor pots....
  • Joy.schottenloher Joy.schottenloher on Sep 23, 2015
    Thank you. Well now I don't have to worry about San Antonio. My house burned down there and inowlive in Ohio. Now it have to learn the different plants for this climate. Yo u have a nice day. Joy
  • Elwanna Elwanna on Oct 14, 2015
    Don't water with tea or coffee as much if ever. I used to love to water with coffee but now only once in a blue moon.
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    • Elwanna Elwanna on May 20, 2016
      @Grangie It is great for the flower bed but it causes knats inside the house. If I have some really weak tea or coffee, I still use it sometimes when I have a sick plant. I guess my ivies used to love it.
  • Judi Judi on Oct 22, 2015
    using a few drops of peppermint in a spay bottle... mist plants... wonderful smell .. and helps deters those pests!
  • Sue914450 Sue914450 on Feb 23, 2016
    I think I've got mine under control. I just sprayed around the soil area with fly spray. When the larvae hatch I'll be waiting with another dose. So far the plants seem ok.
  • Mogie Mogie on Jun 02, 2023

    Are they flies, fruit flies or fungus gnats?

  • Mogie Mogie on Jun 16, 2023

    Are you reusing your potting soil? Use fresh soil.