Potato recipe getting rid of Fungus gnats

In our quest for the latest technology and precision pesticide application mankind will spare no expense or effort to come up with a fail proof method or device to rid us of unwanted pests. Sometimes we need to lean back just a bit and listen to the wisdom and time tested truths that our older generation would love to impart if we would only take time to listen. This little gem comes from a sweet little old lady from some 20 years ago. To look at her you might think she was a bag lady or living on the streets but she had wisdom in a number of things and she imparted some useful pest control tips I still use to this day.

Fungus gnats can be quite bothersome although they are basically harmless. Some of an exterminators worst calls are for gnats and for the do it yourself pest control person it can be as equally maddening. A quick sweep of the web and you can get confused about which pest you have especially if you are trying to identify teeny tiny gnats. Without the correct identification most people try all sorts of different methods before they finally stumble upon the right one that eliminates the problem. I believe sometimes the gnats basically ‘run their course’ and disappear naturally but we coincide the sudden vanishing with our pest control method and from then on are convinced we have the answer.

What a fungus gnat looks like

Fungus gnats most closely resemble the mosquito only much tinier, normally black but some can be grayish. They aren’t the greatest fliers and tend to hang around your potted plants and can often be seen running on the leaves and stems.

Life Cycle

Thankfully the adult Fungus gnat only lives about a week but in that short time she may lay 100 to 150 eggs. These are laid in strings with about 40 eggs per and begin to hatch about 4 days later. The larvae (maggots) are the biggest problem even though we seldom see them. They live for about 14 days and eat the heck out of your plants root system and then move up the stem. From there they move into the pupae stage which lasts about 4 days. The adult emerges and the cycle begins again.


The most obvious control is prevention and that is as simple as not over watering your plants. If you develop a case of Fungus gnats the first thing you should do (after you move the plants outdoors) is to reduce watering. Sometimes you can have good luck with sprinkling Diatomaceous earth on the soil and the tiny sharp shards will cut the larvae thus eventually kill them. They feed in the top layers of the soil so you may need to mix it in slightly. Yellow sticky cards can reduce the adult population somewhat but won’t cure the problem. Pesticides aren’t really recommended because you need to cut off the life cycle and filling the air with a fog or aerosol may make you feel like you’ve done something but it’s hardly worth it to kill a few adult gnats.

Potato Control

This brings us to the use of a potato. The larvae just can’t seem to resist the sight of a freshly cut potato laying on top of the soil. They will move to it very quickly and begin feeding like hungry rats in a dumpster. Simply cut medium thick chunks or slices of a potato and place it on the soil of your potted plant. In 3 or 4 days remove the slice and put in another. Repeat this process until you find no more larvae in your tasty potato trap.

Years ago Dan Quayle got in trouble because he couldn’t spell the word potato and insisted on adding an ‘E’ to it. It was a sixth grader who set him straight which would seem an unlikely source to teach this highly educated man. In today’s world with all our sophisticated equipment and products to solve our pest problems perhaps we should also look to a seldom used source, our seasoned citizens who’ve walked ahead of us all this time.

About The Bug Doctor

Jerry Schappert is a certified pest control operator and Associate Certified Entomologist with over two and a half decades of experience from birds to termites and everything in between. He started as a route technician and worked his way up to commercial/national accounts representative. Always learning in his craft he is familiar with rural pest services and big city control techniques. Jerry has owned and operated a successful pest control company since 1993 in Ocala,Florida. While his knowledge and practical application has benefitted his community Jerry wanted to impart his wisdom on a broader scale to help many more. Pestcemetery.com was born from that idea in 2007 and has been well received. It is the goal of this site to inform you with his keen insights and safely guide you through your pest control treatment needs.

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  • Toji2564

    Awesome!!! Very spoken perfectly..

  • Thank you– I hope it helped.

  • Teresa S

    thank you so much ! I’ve been fighting these “buggers” for toooo long now.  I’ve used the hanging sticky fly strips and have caught a ton of them and also put white vinegar in lids all around my plants (I have too many) and have drowned a ton more but still have some around here and there ! Oh boy I hope to never see these things again.  I never even knew they existed and I don’t know where they came from.  I did buy a bag of potting soil that was outside (in a pile on those wooden thingys) … do you think they were in the bag of Miracle Grow? It was just the regular kind, before they started to make all the other advanced miracle grow (okay).  Any way .. thank you very very much and now my only hope is that I have some potatoes handy ..  if not … store … here I come !!

  • They could be in any soil where the conditions are right and bags like that stored outside usually give them all the right ingredients they need.

    I’m glad this article helped–Thanks for reading my blog!

  • Beeze Kneeze

    I will give this potato trick a try.  I too think I received some fungus gnats courtesy of miracle grow organic potting mix.  Never again.

  • I hope you have success- both with your plants and getting rid of the gnats.

  • Teresa

    Hello Beeze Kneeze. (interesting)  I’ve learned so much since I wrote on here about the fungus gnats.  Although the potato trick may work for some, in did not work for me.  I figured out 3 things in combination that did the trick for me.  Also info about miracle grow.  Email me at tsurratt3@verizon.net so I can tell you everything.  Look forward to your email. (please title it in reference to the gnats so I won’t think it’s spam and send you out as quick as you came in 🙂 .. … seeya