Fruit Flies infesting my plants?!?!

Brick, NJ(Zone 7a)

i've developed what lookto be fruit flies all over my house plants.
they are multiplying, despite my spraying insectisidal soap, and putting all the plants outside for 2 weeks.
ugh. i keep smooshing them, don't know what else to do.
anyone else ever get these and what do i do? stephanie

Ottawa, Canada


When you water your plants do you notice the "fruit flies" more? By this I mean does watering the soil cause the "fruit flies" to fly about the plant?

If so, you probably have fungus gnats. If not, then completely ignore the rest of what I write below.

Fungus gnats feed on decaying organic material, and the larvae also feed on roots. They become a nuisance in large numbers (which sounds like your case).

The most common remedy to get rid of them is to let your soil dry out completely and water less. Also, remove any organic material from the pot such as dead/dropped leaves. Provide only enough water to let the plant live, but not enough for the fungus gnats to feast. I recommend you try this first. And here is the information you need to know.

- Adults live for 7-10 days and lay eggs on top of soil and in cracks along surface.
- The larvae stage last 12-14 days and that's when they are feasting on your roots
- Breeding is continuous and females lay up to 300 eggs per day.

This means that every day you will have new adults and new larvae appearing. Allowing the dirt to dry out and watering MINIMALLY means that in 2-4 weeks you should notice their numbers are reduced.

The second alternative is a little more drastic - make sure you try the 1st one before this. Get some good soil appropriate for your type of plant. Do not get your soil at Walmart or another store, go to a reputable dealer and consult them (they might even be able to offer a better solution that I what I am about to tell you).

Next buy the soil, then keep it separate from your plants. Take your plants and completely submerge the soil in water and remove the soil from the roots. If the plant is small enough wash it as well. This will remove the larvae from the roots and the adults don't like to swim so they won't hang out on the leaves if you dunk the plant. If the plant is too big, then you might want to try the bathtub (after you've washed the soil off the roots of course).

Thoroughly wash the pot (leaving the plant submerged as much as possible) making sure you get rid of all dirt and stains. Dry the pot. Or buy a new pot (same size as existing) and toss the old one in the garbage.

Give the plant another dunk in clean water and put both the plant, pot and new soil in a separate room from the others.

Re-pot the plant using the new good soil.

Repeat the steps for the other plants. And lastly kill any remaining adult you see on spot.

These steps will work to get rid of the fungus gnats; HOWEVER this method causes a LOT of stress and strain on the plants and if they are weak or ill, they may not survive.

I hate to say it, but you also complicated your situation by putting your plants outside. In no way will that get rid of insects. In fact, in putting the plants outside you might have introduced more insects and of different varieties. On the topic of putting houseplants outside, here is my personal view on when you know they should go out. Put your plant on the floor (still in the pot). When it jumps out, walks over to the door, and opens it, then that's the time to let your plant outside. Otherwise, if the plant looks healthy, has nice foliage and is doing quite well, just leave it where it is. :-)

Brick, NJ(Zone 7a)

so funny... the gnats were less outside...but i know now that that was ONLY because they soil dried out.

i have fly paper, and letting the soil dry out for 3 weeks or so. then watering them with hydrogenperoxide/water mix (saw that on a link here).

i hate buggies.
and my houseplants are staying INSIDE forever now... except for the ones i need to throw away. :(
thanks fo ryou rhelp.

Dublin, CA(Zone 9a)

While it is true that you can pick up insects and things when you take houseplants outside, I personally believe it's actually good for them to spend the warmer months outside. After all, there really isn't such a thing as a "house plant", they are all outdoor plants--they just happen to tolerate being indoors better than other outdoor plants, so we've decided we'll call them houseplants and grow them indoors. But they'd still rather be outdoors if given a choice (except in winter of course since they're mostly tropicals).

Melbourne, KY(Zone 6a)

...except if you live in a wooded area, where animals like to dig up and/or munch on your plants. Unfortunately, I speak from experience. :(

(Zone 3a)


I've had great success ridding my "houseplants" of fungus gnats by putting about an inch of play sand on top of the soil. It dries out quickly after watering & for whatever reason, it works! I was given a plant that likes to sit in water all the time so letting it dry out wasn't an option. It went from being a sickly, about-to-die, infested plant to happy & healthy. It has been outdoors all summer (with the sand still there) & no sign of re-infestation! Good luck!


Ottawa, Canada

Hi sjonesartist,

I did some more research on the fungus gnats. As it turns out, they may not be your only problem. As their name implies, they can spread fungus from one plant to another. Some of the fungi they can transport are lethal to plants, two of which the only solution to treat is to use sterilized soil (in other words the plant dies and then the plant, soil and pot must be thrown out).

At this stage, If you haven't already done so, I recommend that you keep your infected plants in a separate room from all your other houseplants and keep your eye on them for about 4-6 months. If any signs of fungus appear (stem, root, leaf rot) then you'll need to use a fungicide. This will generally work for most fungi. I wouldn't worry about this too much, at this time you just need to keep your eye out and watch the plants carefully.

Regarding the comments from others about putting plants outside. Keep in mind that if the plant is not native to your region, then even though it is inside or outside, it is still outside its element. Many plants (certainly not all) grow inside forested or jungled areas. A forest or jungle provide a "tree canopy" and other types of protection similar (but albeit not the same) as the protection offered by a house. Thus the statement that plants prefer to be outside is not necessarily correct. Depending upon the elements outside, a plant may actually not like it at all. What we can say however, is this, plants actually prefer to be in their native habitat. If your house offers some of the same features as the plant's native habitat, then the plant will do its thing. But to assume that the plant will enjoy your back porch or front veranda is a false assumption.

Now, with all that said, I do realize that some people have some pretty inhospitable homes, too little light, not humid enough or too humid and they might keep the air conditioner too cold etc etc. In those circumstances then it is better to put the plants outside - but remember, outside means there is less protection from bugs and other infections.


Richmond, CA

I'm having a problem with them.

The sand thing makes sense. Some of my plants have a good thick layer of bluestone at the top of the soil and don't have problems.

I used some nematodes last week (re: too early to tell if they work) but I'll follow up with sand too.

Niles, MI(Zone 5a)

There is something my Grandmother used and I do the same thing when I get little "pests". I soak the pot and plant in a bucket of water that has dish soap in the water. Depending on the size of the plant and pot I usually use a 5 gal bucket , half full of water and 1/4 cup Dawn, let the plant set in the water, until the bubbles stop and then drain and wipe the leaves and stem with the same water on a paper towel. Get rid of the gnats for me. I use this remedy on all my plants from africal violets to palms.

Sandy Springs, GA

I had a fungus gnat problem about 2 weeks ago and I went to a local plant store for advice. The plant store suggested that I buy "Systemic Granules Insect Control". It is a powder that you sprinkle and work into the topsoil of your plants and it works for up to 8 weeks as you water. Basically it kills any gnat larvae in the soil. I killed adult gnats as I saw them and I haven't noticed any more gnats flying around. I thinks the solution will work best if you re pot the plant. If you use the same pot just make sure that you clean and disinfect it thoroughly. I washed all of my pots twice...once with soapy water and again with bleach and water.

My gnat problem was not very severe as I started my treatment at the first sign of the gnats. I'm not sure if it will be as affective for you.

(Bre) Sellersville, PA(Zone 7a)

annabelle - so do you just put the whole plant in the water/soap bucket? Doesnt the dirt get all over the plant? Or do you just put the pot in? How does the soil & roots tolerate the soap?

Niles, MI(Zone 5a)

just set the pot in the water, just a little over the top of the pot and let it bubble. As soon as it stops pull out and let drain

(Bre) Sellersville, PA(Zone 7a)

great! I think some of my houseplants will love a bath

Cardiff, United Kingdom

Helloo, I've got the exact same problem as all of the above people, and I've read each comment, Ive had these green flies for about a week now, I was going to try the bucket/bubble method but I'm scared my plant might die, Its a cactus plant, i think its called a Euphoria?, It looks quite fragile, Its a cactus with pink flowers growing on it too, I've only had it about 1 1/2 months and i potted it a week after having the plant with compost..and these pests have only now come along, i water it every 2 days? Is that too much? Or does it cause the bugs to come?...Could you please give me the best method to get rid of these bugs...There starting to perch all over my bedroom :(

Toronto, ON(Zone 6a)

Hi! I tried the peroxide, the soap, and the baths without much success - they just kept coming back! The only thing I didn't try was the sand, but only because I didn't want to buy a huge bag of it for just a couple of small pots.

Then someone told me about Green Earth's Insect Dust. It took a couple of watering periods but it worked. I did use it in conjunction with those sticky yellow traps, too. Those caught so many of the flies the first 2 weeks that it was just gross when it came time to replace them! Our problem was that the entire floor of our office was getting them so it just took a while for the buggers to peter out.

Dublin, CA(Zone 9a)

RawrltsSarah--every 2 days sounds like too much water for a cactus or a Euphorbia unless they're in a tiny pot outside in the blazing sun. They do not like to bet wet all the time, you need to let them dry out a bit in between waterings. That'll be much better for your plant, plus it'll probably help with the little flies if they're fungus gnats, they tend to only come around and cause problems when there's too much moisture around.

Cardiff, United Kingdom

ecrane3 -- Oh i see, Yeah i wasn't too sure on when to water it, I bought the plant at a Garden center and it didn't have any tips on watering with it...I watered it Wednesday last, so I'm letting it dry out in the conservatory now, its much hotter in there, when do you think is best to water the plant? Every week etc?
Thanks for your help :)

Dublin, CA(Zone 9a)

There are a lot of variables that go into how frequently you have to water it--temperature, humidity level, what type of potting mix you used, how much potting mix there is relative to the amount of roots, etc, etc. The best thing to do if you can get your fingers in the pot without sticking yourself on thorns is to stick your finger down a couple inches below the surface and see how it feels--if it's at all wet then hold off on watering, but if it feels really dry then you can water it. If you can't get your fingers in there, then you'll have to learn to judge by the weight of the pot, when the plant has dried out the weight of the pot will be a lot less than right after you watered. I can always tell which of my containers need water by picking them up, but until you get a feel for the right weight it helps if you can do the finger test too.

Cardiff, United Kingdom

Aww right ill defiantly start doing that :)
Thanks very much! Which method do you think i should use for getting rid of the Fungus Gnats? all of the above sound good, but i don't want to drowned or kill my plant, also at the moment i got normal compost in my pot...That's also used for outside plants...Should i re-pot with different compost? or would that kill my plant, I'm going to put Sand on top of the compost once the gnats are gone, that should create a barrier for my plant then :)

Thanks for your help :D

Aberdare, United Kingdom


Think I just bought a bag of potting compost full of fungus gnats. Just opened it to re-pot a sick plant and saw lots of tiny flies inside (last thing my sick plant needs). Really annoyed and its a well known brand to (not sure I should mention which). Do you think I can take it back to the DIY store for a refund inspite of opening it. Really lucky its a re-sealable type bag, so I closed it a bit quick (one or two escaped).

Thanks : )

Dublin, CA(Zone 9a)

It's worth trying to take it back, you can tell them it had a bunch of bugs in it and see what they'll do. If they don't give you your money back (which they may not since it wasn't their fault there were bugs in it) you could call the toll-free number on the bag to talk to the manufacturer of the product, I don't know about the UK but here if you do that, the mfg will typically send you a refund or a coupon for a replacement product or something along those lines.

Medford, NJ

I found that killing the larvae by watering with very hot tap water does the trick. I wouldn't do this to plants that have very sensitive and/or shallow root systems, though, and to be on the safe side, I just use enough hot water to wet the top inch or so of soil.

I don't care to use chemicals of any kind, especially indoors. The best thing to do is not water so much, and for the most part, I only water my plants when they are dry, so my fungus gnat problems are minimal. But every now and then, usually after bringing a new plant in that may have them, I get a mini infestation, and the hot water for a few weeks takes care of it every time

Dartmouth, Canada

On Christmas Day my friend was at the sink and noticed my orchid (in bud) was covered with tiny bugs so she washed the whole thing, blooms, leaves and all with soapy water. It killed the bugs for a while, but then the buds dropped off and never did open. I repotted with fresh bark & moved it to another location & today I noticed two new stems coming out, but I see gnats flying around it again. Should I spray with soapy water again or try peroxide. Any comments

Dublin, CA(Zone 9a)

I'd try peroxide, but also make sure you're not watering it too much. I've never had problems with the gnats except when I was watering a bit too much.

Poughkeepsie, NY(Zone 6a)

Go to the garden center and buy a package of "Mosquito Dunks". Put a quarter of one in your watering can. Water with this for a few weeks, it will kill the larvae in the soil. USe sticky trap for the adults. It is safe to use around people and pets. It contains BT.

Greenacres, WA

Hello I have never heard what the tiny bugs were. I had a plant with bugs in the soil.
since I didn't know what to do I put the extra end from my pet flea collar in it. It Worked they left. I was so glad.

Poughkeepsie, NY(Zone 6a)

Some soil bugs are Soil mites or springtails. Both are harmless to plants, they feed off of organic matter in the soil. If one of those are the case allowing the top half of the soil to dry out will help.

Irving, TX

This is a really super old thread, but for other people searching, I'm going to post. I live in a tiny apartment and just got some new african violets. Most of my plants are outside, save a croc fern and a few orchids, but as soon as I got the african violets I started having problems. I don't think the AV brought them in because I've bought from this grower when I was living elsewhere and had no problems. But I mixed new moss and perlite from a big box store, coulda been that.

This is my plan, if I can get my hands on everything. I'm gonna put three layers in my pots; the granulated stuff, diatomaceous earth, and sand, and then I'll water with "mosquito dunks".

My living room is basically my dining room is basically my tv room is basically my conservatory. And I'm obsessive compulsive, I found a roach the other night, and to send a message to any of his buddies that may be around, I pointed him out to my cat, who plays with dead bugs for days on end. We feed crickets to our leopard gecko, and she occasionally gets one for a treat, is how I know this. I can't have these guys flying around while I'm cooking or eating. So if this plan doesn't kill them, I don't know what will.

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