Getting Rid of Fruit Flies and Fungus Gnats

There is no doubt that one of the MOST frustrating things about vermicomposting (and the thing I’m convinced is one of the real limiting factors preventing much more widespread interest in this field) is the other “critters” that can take over our vermicomposting systems. A couple of the worst offenders are undoubtedly fruit flies and fungus gnats.

I am definitely an advocate for “ecosystem rights” in a lot of ways (haha) – and really try to hammer home the point that a vermicomposting system is NOT just about the worms – BUT, I don’t have a whole lot of sympathy for the plight of these pesky flying varmints. Unlike with many of the other organisms that can pop up, such as mites, springtails, and white worms, it’s easy (for me) to think of fruit flies and gnats as “invaders” – we certainly DON’T need them involved in the process, and I certainly don’t need clouds of them up my nose!

Well, it just so happens that I have a fairly healthy population of both of these guys at the moment, so I’ve decided to have some fun (at their expense – MOOOHOOOHAHAHAHAHA!!). I placed an order for some parasitic nematodes (Steinernema feltiae), and set up a couple of fruit fly & gnat farms (pictured above) I hope to turn into nematode rearing cultures. As some of you will recall, I have tested S. feltiae before (see “Steinernema feltiae – Fungus Gnat Killer“) and I actually found them to be quite effective – at least initially. The issue is that the effectiveness seems to decline over time – undoubtedly due to the fact that the nematodes end up getting killed. For one thing, I discovered that scientific research has shown that the passage of these nematodes through an earthworm’s digestive system kills them (see “Steinernema feltiae and Red Worms“). I’m sure there’s also a fair bit of competition/antagonism due to the wide assortment of other organisms that can live in the rich composting environment.

Aside from wanting to work a bit harder at creating ongoing cultures of these nematodes (thus meaning I can apply them over and over again), I’m also VERY interested in once again testing to see if these nematodes will attack fruit fly larvae as well. I did set up an experiment to test this out last time around (see “Steinernema feltiae VS The Fruit Flies“), but I’m pretty sure conditions (outside during the summer) were too warm for proper testing.

Anyway…I will certainly keep everyone posted on my fun nematode experiments, but if I might shift gears a bit here, I think it’s not a bad idea to spend more time on this “Getting Rid of Fruit Flies and Fungus Gnats” topic in general (especially since a lot of you likely assumed that’s what this post was going to be mainly focused on).

Let me start by saying that both of these guys are a ROYAL pain once they become well-established, but of the two it’s the fungus gnats that are actually the most frustrating (in my experience). Unlike fruit flies, it can be very challenging to remove their “food source” since the larvae will feed happily on a very wide assortment of decomposing materials. You’ll likely need to be a lot more patient and thorough with your eradication efforts. On the plus side, really bad gnat infestations don’t seem to be nearly as common as is the case with fruit flies.

In both cases, PREVENTION should definitely be a very high priority! There are lots of different ways to lessen your chances of getting invaded. Here are some things to consider:

1) Observation – simply keeping your eyes open for any signs of small flying insects in your house is certainly an important part of the process! Fruit flies will likely first make their presence known in the kitchen – especially if you happen to keep fruit out in open bowls etc. Be especially wary of fruit from warmer regions – bananas, pineapples, melons are all regular fruit fly sources, especially if they have any sort of injury/lesion/disease. With fungus gnats you will want to be most careful with any potted plants and soil that you bring into the house since it’s not uncommon for them to already contain larvae and/or eggs. A good rule of thumb with your indoor potted plants is to let them dry out a fair bit between waterings. Constantly moist soil can become a prime gnat breeding ground. Generally, I’d also recommend keeping your worm bins a good distance away from any of your houseplants.

2) Careful Food preparation – This one applies more to fruit flies than fungus gnats. One thing I really recommend, if at all possible, is to freeze all your food scraps prior to adding them to your worm bins – especially in the case of uncooked fruit/veggie waste, and extra-especially (haha) with these materials that have also been sitting out for a period of time (in fruit bowls, scrap holders etc etc). Freezing these wastes will actually have a two-fold advantage. The obvious benefit will be the killing of any fruit fly eggs/larvae that happen to be in the material. Secondly, freezing can be a valuable way to start the break-down process (water expands when it freezes so this tends to rupture cell walls etc) thus making it easier for microbes to invade. You might want to let the materials thaw before adding them to your system though, since a lot of water can be released plus you don’t want to shock the system with a rapid temperature drop (could be helpful if your system is overheating though). Apart from freezing wastes, I also recommend chopping up (or even blending) materials before adding them since this will make them a lot more microbe- and worm-friendly, lessening the chances of other organisms gaining a strong foot-hold. On a related note, just generally feeding in moderation can go a long way towards avoiding any critter population explosions.

3) Physical barriers – I highly recommend always keeping a really nice thick layer of bedding materials up above your main composting zone. While this certainly won’t completely stop fruit flies and gnats from getting down below to lay their eggs, it CAN at least be a deterrent. It can also help to mask any odors that can attract these insects. Of course, having lots of bedding in your bin can also just generally be a great way to maintain a healthy environment, since it soaks up excess moisture, provides more worm habitat, increases air flow, and helps to balance the rich food wastes being added. You also may want to cover up your air holes with some sort of fine screening material, or even enclose the entire system in a big mesh (think mosquito netting) bag – perhaps a little extreme, but at least your chances of ending up with an invasion will be greatly reduced.

I think it’s safe to say that you should expect to be invaded by one or the other of these flying varmints at some point during your vermicomposting journey (or more realistically, BOTH of them – many times over! haha), so let’s now talk about different ways to deal with them once they become established!

When I’m not my usual mellow, laid back self (or otherwise engaged in various experimental pest breeding programs – haha), I like to employ a multi-pronged approach when attempting to get rid of gnats and fruit flies. Here are some of my suggestions:

1) Traps – various types of traps can serve as reasonably effective passive methods for capturing flying adults. They can also serve as valuable early warning indicators if you set them up before you get invaded. A very easy fruit fly trap can be made by putting a small amount of apple cider vinegar (or wine vinegar etc) in a jar with a tiny drop of dish detergent (reduces surface tension) and then covering the opening with plastic wrap before punching some small holes. Fruit flies will crawl through the holes and drown in the vinegar. Interestingly enough, I’ve discovered that these traps can also catch a fair number of fungus gnats as well – so I highly recommend setting some up either way.
Another type of trap that seems to work well for gnats is a sticky trap – especially one that’s positioned close to a light source. I’m not sure why, but gnats seem to be much more attracted to light than fruit flies, and even brightly colored sticky traps seem to draw them in. Some of you may recall my experiment with fly paper (hanging near a light bulb), and just how effective it ended up being for attracting gnats and bigger biting flies (see “Fly Paper – A Must-Have Vermicomposting Tool“).

2) Vacuum Cleaner – I’m sure this one will cause some snickering among those uninitiated in the ways of the the fly ninja assassin! (haha)
Joking aside, this is a phenomenal way to rapidly reduce the population of adult “breeders”, and thus greatly reduce the number of eggs being laid in your system. I highly recommend doing this at least once a day for best results. Aside from literally opening up your bin with vacuum nozzle in hand, also make an effort to round up as many of the roamers (those flying around your house) as possible. Again, a nearby light source will likely be a good place to start when hunting fungus gnats, and you may find a herd of fruit flies gathered around your fruit bowl or food scrap holder (speaking of which, you may want to throw scraps straight into the freezer once you have fruit flies in the house, since they will quickly make these containers a prime-time breeding ground if you don’t). It’s also pretty easy to make a powerful fruit fly attracting system (similar to the fruit fly farm shown above). Simply add a bunch of fruit scraps to a large plastic water/juice/pop bottle, along with some bedding materials (so it doesn’t get too sloppy and foul in there), then create a LOT of tiny holes using a pin or something similar. The idea is to allow odors out, while preventing fruit flies from getting in (although, it’s unlikely they’ll get back out even if they DO manage to squeeze in somehow). Fruit flies will congregate on or near this system and you should be able to vacuum up a lot more of them all at once as a result.

3) Remove Excess Food | Stop Feeding – As mentioned earlier, this is going to be a much more effective strategy for fruit flies than for fungus gnats, since gnat larvae don’t rely upon food wastes for their sustenance to the extent that fruit fly larvae do. Nevertheless, this is still a recommended approach for gnat invasions as well since every little bit helps. Feel free to continue adding bedding materials though – this can help to keep your worms alive without helping out the gnats and flies.

4) Let the system dry out a fair bit – This one will be especially helpful with fungus gnats, but should also help with fruit flies as well. The larvae of these pests thrive in wet waste materials and tend to be a fair amount more sensitive to drying than even the worms themselves. Not everyone will likely want to go this route, however, since it will more than likely require that you leave the lid off of your system for quite awhile (obviously resulting in more gnats and fruit flies being able to escape into your home) – but you might use it as a final step in the process, once the population of adults is clearly on the decline.

Ok – well, that basically covers some of my primary ways of dealing with these pests. Obviously various forms of biological control could be included in that list as well, but really the only promising option I’ve come across thus far is the use of parasitic nematodes – and again, I still need to test out this approach a lot more before I can provide a solid assessment (stay tuned)!

One last important thing to mention – most of what I’m suggesting here is intended for those with indoor systems. Unfortunately with outdoor systems there really isn’t a whole lot you can do to prevent either of them (well ok – you won’t likely end up with fruit flies if you aren’t using any sort of fruit/veggie waste), or get rid of them once they are established. I don’t personally find them nearly as frustrating in outdoor systems (not quite so “in your face” I guess), so perhaps this isn’t really a big deal anyway – but figured it was worth pointing out.

I am VERY interested to learn what approaches others have found to be successful for preventing and/or getting rid of fruit flies and fungus gnats – I’m sure there are plenty of effective methods not mentioned here. It would be really cool if we could turn this post into a sort of “ultimate” resource for dealing with these annoying pests.

Please share your ideas and methods below!

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    • Rhonda
    • August 16, 2013

    Hello Carolyn,
    I didn’t seem to see your message yesterday. Thank you for sharing your experience with me! That sounds like exactly what I am doing right now as well. It sucks waiting but they seem to be few in number each time I open the bin lid now, yay! I have stopped feeding my worms for now and am going to try and harvest some for a new bin soon. I think what happened in the first place is that I only had a small layer of bedding on top and my holes were not mesh covered. I put the bin outside and the flies must have gotten in that way to lay eggs. Now I have my bin holes mesh covered and a LOT more bedding on the top layer! I also have a container with the apple cider as previously mentioned in my bin for the fruit flies. Live and learn, now I know better than to leave my bin unprotected! Never again! haha

    • Rob
    • December 29, 2013

    I see many posts here and other places about freezing scraps, but there is one here about microwaving. Is there a downside to the microwave method?

    • Diane Peel
    • January 22, 2014

    I am reading this as a prospective worm farmer, but keep wondering why there is so little mention of BT israelensis found in mosquito dunks (which I used for years) Gnatrol, and other drenches as mentioned by Carol #4I clear back in December 20I2. I usually grow lots of amaryllis around the holidays and allow my houseplants to enjoy the outdoors during our short summers; so fungus gnats are not strangers at my house. I am now using Gnatrol WDG and love it. It’s container tells me how much to put in my water each time I water to control the infestation of fungus gnats I am trying to control – moderate this time and due to some new houseplants I bought on sale.
    I’ve used mosquito dunks for years, but never had a really firm Idea of how much I should use except what I could read online. The dunks are meant for mosquitoes so there’s no help there. In addition to the dunks I’ve tried many other ways of controlling f.g. sand and d.e. on surface,etc. Improving my watering habits became my first line of defense that and the Gnatrol (and the dunks before it) provided the most help. It will keep the tiny gnats/flies from being a dealbreaker in my quest for more and better compost. This is something my husband sees no need for – but he is very much against breathing and eating or otherwise ingesting gnats or flies.

  1. Hello All, there have been some great comments here.

    Below I describe the methods we successfully use to get rid of fruit flies.

    Fruit flies are attracted to fruit and as such can often be found in worm farms, compost heaps and worm bins.

    Although they are essentially not harmful to the worms they can become a nuisance if they are allowed to multiply.

    They can be identified by plump bodies that are usually pale brown or orange and a slow flight. They are between 1 to 2 mm / 64th to 32nd of an inch big.

    Mature flies lay their eggs on the peels of fruit, especially bananas. Those eggs are to small to be recognized by the human eye. When the conditions are right (warm and humid) the flies hatch and can quickly multiply if the environment is to their liking.

    There are a few ways to reduce or even eliminate the fruit fly population in your worm bin.


    1.) Place all your fruit peels and rotting fruit that you want to add to the worm bin over night in a freezer before you put them into your worm bin. This will kill all eggs that are on the fruit and peels.

    2.) Place the kitchen scraps for about 1 minute into a microwave oven to kill eggs that might be on the fruit and peels.

    3.) When you want to add fruit peels and fruit to your worm bin dig a trench through the center of the worm bin and dump your waste into the trench. Then cover the worm food with already processed worm castings.

    The casting will act as a natural barrier against the flies.

    Another way to keep those tiny invaders out of your worm farm is to catch them with a trap.

    To build a low cost fruit fly trap.

    Take a large empty Soda plastic bottle, cut of the neck just above the place where the round turns into the straight line.

    · With a sharp nail or scissors punch 5 or 6 holes 2 to 3 mm / 32nd to 48th of an inch in diameter into the side walls of the bottle about 10cm / 4 inches above the bottom of the bottle.

    Throw a few banana skins into the empty bottle.

    · Place the cut off top peace upside down into the opening at the top of the bottle base. It should look like a funnel now.

    · Make sure that it fits tight and no gaps are left open.

    · Attach the funnel top to the bottle base with some clear sticky tape.

    · Place the trap a few meters away from the worm farm on an elevated place.


    It’s that easy! You can prepare a few of them slightly modified and place them in different locations to find out which works best.

    Now open the lid of the worm farm and chase out as many of the fruit flies as you can than close the worm bin again.

    The flies which have an excellent sense of smell will get attracted by the banana skins to the traps and crawl into the small holes on the side or the funnel opening at the top.

    Most of them will not find the way out again. You should catch most of the fruit flies that have been inside your worm bin within 48 hours.

    Once your traps are full either release them somewhere else or wait till they are dead and feed them to your worms.

    If there are more flies left set up the traps again till you have caught the remaining ones.


    Fungus Gnats – are as well members of the fly family and are similar in size and looks to a mosquito.

    They have a black slender body which distinguishes them easily from Fruit flies.

    They get attracted by fungi and moisture and can be found in and around compost heaps and worm bins.

    If you want to reduce the number of gnats in your worm bins

    try to reduce the moisture levels on the surface areas of your bins (be careful and remember that the worms need a moist environment to live in.)

    Or try to reduce the levels of food that you add to the worm farm.

    We never really had a major problem with gnats and usually just ignore them.

    Kind regards and happy worming

    • rou1
    • January 26, 2014

    Fly paper work well in worm bins.It catches plenty of unwanted critters.

  2. Hello rou1,

    that sounds interesting. Can you explain how this flypaper works?
    Is it sticky?

    • Kenneth
    • January 28, 2014

    Linda, what is SC vinegar

  3. I’ve heard the respiratory system small fruit flies have are weak. Does anyone know..
    if I set a small contained fire in a worm bin, fire being in a container.. so smoke fills worm bin and kills small fruit flies. Will this also kill the worms.. or not?

    Any experience with this?

    Vinegar solutions, sticky traps, and other DIY systems don’t work for larger scale home worm bins.

  4. Hello Anthony,

    compost worms are breathing through their skin and when the smoke penetrates their bedding it might very well kill them as well! Remember that compost worms are top feeders and will usually be close to the surface of your worm bin.

    Consider fruit fly traps, to bury your kitchen scraps inside your worm bin and cover them with processed worm castings.

    This works usually quite well. You can as well build some fruit fly traps as I described in one of my previous comments!

    All the best and happy worming!

    • Brandi
    • May 7, 2014

    Thank you for this article. I had my class make some fly traps and followed other suggestions to get rid of our fruit fly pests! I think we have it better controlled after just a few days. Thank you!

    • Sarah
    • June 20, 2014

    Hey Bentley,

    I’ve got a question that I’ve been googling and can’t seem to find addressed anywhere. I’ve got fruit flies. I don’t mind them – they’re isolated in my basement where my worms live. But what about using the compost? I’ve got a nearly full bin, just waiting to be harvested. What do you think about using compost that’s (obviously) got fruit fly eggs in it? Most of my potted plants are on the outdoor terrace, so any hatchlings will probably emigrate or be blown away. But perhaps I should freeze the compost before using on my indoor pots? I’d be interested to hear your take on this. Cheers!


    • Bentley
    • June 30, 2014

    In the case of fruit flies I wouldn’t worry about it (might be a different story with fungus gnats, especially if growing seedlings) – unless there was risk of ending up with a serious infestation in your house (ie you keep lots of fruit sitting around etc). If the plants are outside this should be no problem at all. Plus – their eggs will typically be in the food materials not in the compost.

    • Kathy
    • July 24, 2014

    I didn’t have any fruit flies in my bin that I saw and I always cover it at night. I have shredded newspaper on top of compost. Last 2 mornings I got up checked my bin that’s in my kitchen, it had all this fine stuff on the inside of the lid when I took it off and on the sides of the bin and all over my counter around the bin. First day I thought maybe it was from my shredded paper, just cause I wasn’t even thinking bugs! But took damp paper towels to wipe up and it had a peculiar order and is a light tan. When I moved some dirt around I can tell it’s all through it. No fruit flies or gnats around at all. They are so minuscule but I can c some movement in them. Are they going to turn into flies and or gnats? I will hav thousands of them! Will that many ruin my worms?

    • Jackie Kelly
    • August 1, 2014

    Hi, I am at my wits end. To make long story short, I have moved my worm bin inside for temperature reasons. Everything is perfect and yet I find dead worms on the floor everyday. There was a small lizard in the bin that I finally captured and let go way out in the back yard. My question is…. do lizards create a problem for the worms that make them leave the bin? I am hoping you will say yes then my problem will be resolved.

    • Bentley
    • August 2, 2014

    Hi Jackie – if anything, I’d guess that the lizard would intercept worms that are trying to escape, so fewer would end up on the floor. I suppose that fresh lizard ‘manure’ might not be all that great for the worms – but I’m not sure that would make them want to escape.

    Likely a number of factors at work here. Feel free to email me with more details:

    • Bentley
    • August 2, 2014

    Kathy – hard to say for sure what you are seeing. Fruit fly and gnat larvae would been in food and bedding materials though, so it isn’t likely them. Could be small white worms (aka pot worms), or even tiny mites (I have encountered VERY tiny tan colored mites in my bins before). You may want to cut back on feeding, add more bedding, and increase aeration in the bin. The organisms themselves won’t likely cause any harm!

    • Pat
    • November 6, 2014

    I’ve been using red worms for composting since 2001 and have learned that rinsing off the eggs from the lid of my red worm bin with a garden hose is the easiest way to rid most of the invaders. When they fall to the ground, they dry out and die…hence they are gone or at least minimized. Check often and rinse off…eezy peezy

    • Paul
    • December 30, 2014

    I have some sort of bug (lots of them) in my bin. They don’t fly, but they do crawl very fast for a bug. They are tiny, maybe 0.1- 0.2 mm, kind of an orangey-reddish. It seems most are on the lid and around the upper edge of the bin, but I’m sure they are in the bedding as well. Any ideas as to what they are and should I worry about them? Thanks.

    • Carol
    • January 9, 2015

    I do not have problems with either of the flying insects. Oh, sometimes I’ll see a few fungus gnats, but those mostly stay around my plants under lights. I hang home-made yellow sticky traps and monitor their presence; if I think there are too many I use a Bt soil drench.
    What I have in great abundance in my worm bins are millipedes – countless ones! I know they do not actually hurt the worms, but I am beginning to wonder how much they are competing for food with the worms.
    When I sort out the worms and prepare new bedding, there is no way I know of to get rid of all those millipedes – or at least reduce the population radically. Any suggestions? Thanks!

    • Dan
    • February 24, 2015

    Fruit flies are pretty common in the Fall in NW Iowa before the first freeze, but until this past year I never had them invade a worm bin. Once that happened, it took months to get rid of them.

    My family keeps a compost bucket in the kitchen with lots of produce and fruit around as well, so the flies usually stick to that and ignore the basement where I have a worm condo and a large, 50 gal. worm bin made from the inverted top section of a 350 gal. ethanol tote/IBC container. (The bottom section receives RO filter brine and may one day support an aquaponic system.) I also have a small beer brewing operation down there, and our pantry (also in the basement) has some fly attractions too. Once the flies discovered all this and settled in we had a lot of flies for many months.

    We tried every method to defeat the fly swarm and killed thousands, but they kept coming back. They’d seem to go away, but if we opened some wine suddenly they’d appear. Open a beer tap, and it would flush out several flies into my glass. This was getting pretty bad for entertaining company.

    In the end the only thing that worked was isolation and time. I consolidated all the worms and soil in a large, single storage container and wrapped it with a large dropcloth. After about a month they finally seem to be gone. In the meantime we had to quit saving compostable things, clean our recyclables carefully, or take outside anything that might be attractive to the flies.

    Last I checked there were still flies inside the worm bin, but I’m hoping they will be gone now. I may just wait until spring and take the whole bin outside to the gardens and outdoor composters.

    • Bryce
    • March 9, 2015

    I enjoy optimizing everything in my life and when I saw the Worm Inn Mega I knew I had found the optimal way to compost organic home refuse. And without a doubt it is absolutely the optimal way to vermicompost, especially indoors. My Mega is in my basement, so I had to ensure my wife there wouldn’t be any complications such as smells or stray insects. Fungus gnats are easy to get and even more easy to proliferate. They are annoying but tolerable, I thought, but my wife told me otherwise. I still have the Mega in my basement and there are zero flying insects. Very nice! But how is the key. Easy:

    1. Employ all the get rid of fungus gnat methods you can read about all over the web. Traps, vacuums, freezing food scraps and covering the surface with plenty of torn cardboard, etc. I freeze all my scraps so I just keep my scrap container in the freezer all the time.

    2. the KEY: I add neem meal and karanja meal to my Mega and to all my compost and to all my soil mixes. So all my plants have neem and karanja meal in the soil and I ensure that I routinely add it to the worms. The neem and karanja are both high in nitrogen and other nutrients which results in a more healthy soil food web and they also repel bugs and inhibit their reproduction. So I haven’t seen a fungus gnat or any unwanted insect since getting rid of the ones I could see and since adding the neem and karanja. The worms love it and my plants are healthy which promotes disease and pest resistance.

    • Christopher
    • April 5, 2015

    Just a couple of quick questions?
    What are neem meal and karanja meal?
    Is there a way of actually attracting spiders to the bin?
    Does one Velcro these vinegar traps to the side of a bin?

    • Bryce
    • April 22, 2015

    Neem trees grow in India and I suppose the Karanja trees are in the same area. These trees produce nuts and these nuts are pressed for their oil. Neem oil has been in use for a long time as has many parts of these trees. Neem oil is used to repel insects. The left over seed parts are the neem and karanja meal.

    They also repel and also inhibit reproduction. They are also used as soil conditioners as they have nitrogen and other nutrients.

    I buy mine from Build A Soil in the Denver area. Very reasonable price and free shipping.

    My bin is in the basement and it will attract its own spiders, especially if you have lots of critters. No critters and no spiders.

    Set the vinegar anywhere near will work.

  5. Food grade diatomaceous earth has worked for me. no mites and no flies/fruit flies as long as I’m diligent about it. One drawback is that it washes off rather easily. I usually sprinkle it on the fruit and then cover everything with more bedding. Additionally, I mix it with oyster shell, which stretches it out a little and keeps it from clumping up and turning into glump, which doesn’t really provide any benefit.

    We actually had all kinds of little flying critters in our yard. Maybe it had something to do with the dense clay soil that we have here providing all kinds of little puddle microclimates for them to breed in, but we had skeeter eaters hovering around our yard and by all our lights all the time. It freaked out my daughter. A light spraying of FGDE cleared all that up.

    Now they occasionally show up, but quickly disappear in a day or so.

    A quick question for some of the more experienced members, I’ve heard that some people only use cardboard. Is there some special considerations for this practice? My area has plenty of decaying fruit to go around, just wondering about this style of growing. thanks for all the excellent info

    • Dave
    • July 15, 2015

    We had the fungus gnats this spring, and I used sticky traps and the vacuum cleaner. The adults seemed to enjoy breeding on the white ceiling of our living room, so I hooked enough tubes together to reach it, and just walked around with the vacuum cleaner sucking them up. With the sticky tapes doing their job REAL WELL, and gnat patrol twice a day on the breeders, we were able to get rid of them within a week or so. There sure were a bunch of them. My wife was not happy

    • Mark from Kansas
    • July 16, 2015

    I have a Worm Inn indoors. The zipper broke and I have to clamp it shut, I got a lot of complaints about the gnats flying around the house.
    There was an earlier post about using gerbil bedding in a bin. My son has some gerbils that generate some really nice bedding. I put 2 inches of the gerbil bedding on top. No gnats, the worms are thriving, and most important of all: happy wife = happy life.

    • Andi
    • August 6, 2015

    I have an indoor worm factory that got infested with fungus gnats when we brought home a poinsettia last winter. I tried for months to get rid of them… red wine vinegar traps, sticky paper, reduced feeding, letting the bin dry out, etc. The sticky paper cut down the population dramatically, but there was still plenty of gnats inside the bin and I was getting extremely frustrated.

    However, my bin is now gnat-free and my worms are thriving. This is what I did:

    I made a cover for the bin using cheap curtains sewn into a cube shape to keep the gnats from getting out and anything else from getting in.

    Then I took an empty worm tray and lined the bottom with a thin layer of newspaper, and added about 2 or 3 inches of shredded paper.

    I filled a small spray bottle with water and added peppermint oil, peppermint extract, and clove oil and sprayed the shredded paper until it was damp. I put the tray on top of the bin and re-sprayed the paper every couple of days to keep the smell fresh. I didn’t know if the worms would like the minty paper, so I try to keep it out of the bin.

    It took about one week to see any results, but after about a month I didn’t see any more gnats in the bin. It’s been a few months now, and my worms are still gnat-free, but I still keep the minty paper on top to prevent another outbreak.

    • rijk gupta
    • October 2, 2015

    Have you seen anybody try using Bacillus thuringiensis israelensis? They come in those mosquito dunk discs and a granulated form.. I have seen the dunks used by soaking them in large containers of water and then using that water to water container plants in greenhouse situations, and eradicating fungus gnats.. Could be used in same way in a worm bin.. They also make the dunks in a granular form that could be scratched onto the surface of a worm bin as long as there is no harmful interaction between the 2 species.

    • Bentley
    • October 2, 2015

    Hey Rijk!
    I have played around with the dunks (similar to approach you mentioned) a bit but did not really see any serious results. But you make me want to try it again! lol

    • Steven Goddard
    • November 24, 2015

    I will make this brief:
    Search for fruitfly lifespan. An associated article shows an experiment of the effects of sweeteners on fruitflies done by a 6th grader. He found that Truvia killed fruit flies.
    So I tried Truvia in my wormbin and it works! AND the worms are not harmed.
    You should try it and if it works for you, spread the word: No more fruit flies in wormbins.
    Steven Goddard

    • Mitch
    • November 25, 2015

    Steven; So, do you sprinkle the Truvia over the worm food? Or do you put it in water, or what?

    • Melody
    • January 10, 2017

    HELP! I stupidly put several rotting bananas in my worm bin, which I am still trying to establish. I have had the worm bin for a few months, and it seems to be doing well. I opened the bin today and there are fruit fly eggs (i assume) – thousands, if not more. I have no idea how to fix this problem without harming the worms. Reading through all of the comments on this page seems daunting, and would love any input from anyone.

    • Bentley
    • January 10, 2017

    Hi Melody
    You won’t likely actually see fuit fly eggs. If these things are round, shiny and white, they are likely a type of mite very common to vermicomposting systems. Just generally, if you are worried about food you have added to your system, I recommend tossing it in a bag and letting it sit in the freezer for a day or two. This way you are guaranteed to kill off any FF eggs that might already be in the peels etc.

    • Melody
    • January 10, 2017

    Bentley- thank you!! So I am thinking my solution may be to take the bananas out, and put a small diy fruit fly trap (i do have some of those buggers flying around in there) on top of the dry leaves I have as a top. I read somewhere that it’s ok to spray diluted neem oil on the eggs? These eggs are covering the inside of the bin, mostly above the leaves.

    • margie stephens
    • January 10, 2017

    we had a serious fruit fly infestation that we ended up getting rid of completely–took the bins outside and moved all worms into a bucket–cleaned all bins using hose on full—moved worms back in–since then we keep a container in the freezer and all pre-worm stuff goes in it to become frozen solid before going downstairs (basement) to the worms–absolutely no fruit flies since then–over a year now

    • Cathy Fredericks
    • July 14, 2017

    The best way I found to get rid of millions of fungus gnats is to wrap your bin in two layers of row cover cloth. Put one all around the bin and tie or tape it off. Then put a second layer around it slightly off from the other one. Because the adults get into one layer but get stuck between the layers they can no longer mate. It took about 3 full weeks but it killed off all adults and after the larvae hatched killed them. No traps, no vinegar, just row cloth. A J. Finch has a video on utube on it and it works. My one bin had millions. It worked completely. Never have had another one.

    • Saroj Gilbert
    • September 22, 2017

    Did the nematodes harm the worms at all?

    • Bentley
    • October 7, 2017

    Hi Saroj – these nematodes to not harm worms at all. If anything, the worms eventually kill THEM off.

    • Charlie wilson
    • August 27, 2019

    I have two wooden worms bins one with red wigglers and one with euros in my air condition shed. The bins are too large to move outside and I need to bomb my shed for fleas and ticks because my dog also stays in the shed. Any suggestions on how I could protect the worms while I bomb it would be appreciated

    • Selina
    • May 12, 2021

    I have been doing inside vermicomposting for 10 years thanks to this site. I have had three gnat/fruit fly explosions in total. The first one was when I started a couple months in and I couldn’t deal with it. Adding paper, vacuuming, traps, freezing food first. I battled but they won the war. It ALL had to go!!!! Moved apartments eventually, tried again. About a year later and BOOM!!! They’re back. Grrr. So I taped over the drill holes and I covered it up in a towel and walked away. Ugh. Four weeks after their quarantine lockdown, the little, flying jerks are no more. Woo hoo!!. My worms are still just fine. Now many years later, I’m a household of four, and it’s in a dark storage tote with just a towel on top. No extra holes anywhere. No smells, no flies, no ants since then. Absorbs extra moisture, check. Barrier preventing them from my air space, check. Keeps worms dark and contained, check. Air flow even tho restricted, check

  6. After I initially left a comment I seem to have clicked the -Notify me when new comments are added- checkbox and from now on whenever a comment is added
    I receive four emails with the exact same comment.
    There has to be a way you can remove me from that service?
    Thanks a lot!

    • Bentley
    • September 15, 2021

    Hi Stephaine (and anyone else in same boat)
    There should be a link at the bottom of the email notifications received that allows you to manage your subscription to a given post. I looked up your address and it said it wasn’t subscribed to any posts – but feel free to email me if you are still having issues with this. Thanks!

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