Non-Toxic Fruitfly Spray

newbie314(Z9 CA)December 5, 2005

I have an issue with too many fruit flies and fungus gnats.

Even covering the bin with fresh paper doesn't help much.

I have placed velco on the rim of the bin and attached no-see-um netting.

All the bugs get trapped in the bin, but I don't want them to reproduce in there.

I try spraying with a small jet of water from a spray bottle, but don't know if the kill ratio is any good.

Is there a homemade spray I can use that will kill the flies but have no harm to the worms below.

Maybe a homemade citrus (acid) spray, maybe a crushed egg shell(base) spray.

Thanks for your advice (bin is in-doors, don't want the wife to relegate the bin to the garage or outdoors.)


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sqh1(z7 NC)

What kind of bin do you have? In general, what is your feedstock? With answers to a few is on the way..:)

    Bookmark   December 5, 2005 at 7:59PM
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newbie314(Z9 CA)

Pocket feeding.
The usual stuff newspaper and foodscraps.

    Bookmark   December 6, 2005 at 11:17AM
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Frogonalog(8 North FL)


Some people here recommend microwaving fruit waste before putting it in your bin to kill any eggs that have been laid on the skin.

You could try a fungus/fruit fly trap with a piece of banna or some cider/vinegar and a drop of dish detergent. See below:

If you have some yogurt cups you can do the same thing. Put in a little cider. Get cling wrap or sandwich bag and poke a few small holes in it then secure it over the cup opening with a rubber band. Empty the dead flies every few days. You may want to replace the cider/vinegar when you do this.

Hope this helps.


Here is a link that might be useful: University of Kentucky, Entymology

    Bookmark   December 6, 2005 at 12:10PM
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I notice I don't have fruit flies around my fruit if I wash the fruit with a steady stream of water right after I bring it home.

    Bookmark   December 6, 2005 at 12:45PM
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newbie314(Z9 CA)

I made a new trap a few days ago, sandwich bad around yogurt cup (did that in the past).
Looks like the fruit flies took to it.

I now have placed the trap in the bin, to hopefully bring the new flies into the trap.

Don't know why, but those fly even crawl up through the paper.

Used a vacuum cleaner today to suck up a few.

Will stop feeding the worms for another week to reduce contamination.

    Bookmark   December 7, 2005 at 1:44AM
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newbie314(Z9 CA)

Anybody know why these flies are able to crawl though all that paper.
It's a real pain.
Maybe I need to put a good 2" in of dry paper

    Bookmark   December 9, 2005 at 2:50PM
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newbie314(Z9 CA)

Bad news. The bins outside :-(
Too many flies.
If my bin starts behaving, I may be able to bring it back indoors.
don't worry about winter too much here, 32 is the lowest.
But summer 90+.. :-P

    Bookmark   December 11, 2005 at 12:35PM
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Different things work for fruit flies vs. fungus gnats.Fruit flies have red eyes, fungus gnats don't. I think the vinegar traps work for fruit flies, as does burying and freezing the food, but I know these things don't help with fungus gnats. I had a MAJOR fungus gnat infestation which I resolved with repeated dousings of BT(5 applications, each a week apart) which I got from Gardens Alive. I encased the whole bin in an envelope of mosquito netting and that, at least kept the problem inside the bin.
good luck!

    Bookmark   December 11, 2005 at 3:32PM
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Kelly_Slocum(sw WA state)

Newbie, fruit fly and fungus gnats in a worm bin, for the most part, enter the system as tiny eggs and larvae attached to the peels of uncooked fruits and veggies. We INTRODUCE them to the bin each time we feed. The dark, damp bin environment rich in fungi and decaying vegetation is an ideal breeding ground for these flies, thus their populations can quickly explode to impressive and annoying numbers. Burying the bin contents under mounds of paper, a control method widely touted on internet forums, has little or no impact as adult flies can easily crawl up through the spaces in paper shreds, or simply rest beneath layers of paper sheets until they are lifted, and the fly larvae appreciate the moisture-holding, light-inhibiting paper layers as much as do the worms. As it appears you've discovered on your own, paper layers have little impact on small fly populations. Fruit fly traps set in the bin, another commonly suggested control measure, are essentially useless as the bin itself is, by definition, a massive fruit fly food source, leaving little incentive for adult fly numbers sufficient to decrease the total population to enter the trap.

The best way to control fruit flies and fungus gnats begins with prevention.

Again, these small fly species enter the (indoor) bin as eggs and larvae on the peels of uncooked fruits and veggies. Pre-treating feedstock before feeding it to the system by either microwaving until it bubbles and pops (you may need to stir then re-microwave once or twice, dependant on your microwave, to ensure all of the feedstock gets sufficiently hot), or freezing solid for three days kills the eggs and larvae, preventing fly populations from being introduced to indoor bins and establishing communities.

If the bin becomes infested with fruit flies and/or fungus gnats they can be controlled by initiating pretreatment methods to stop the introduction of new populations in conjunction with the application of beneficial nematodes. These nematodes feed on the fly larvae, interupting the reproductive cycle in the bin, and usually take about 10 days to bring the fly population under control. Keep in mind during this control period that any fruit of veggie left on a counter top, and any damp sponge or dishrag, unclean sink drain, or laundry hamper full of damp towels can become a fruit fly breeding site, so try to avoid making these sites available.

Nematode control is quite effective, but is not a quick fix and MUST be performed in conjunction with pretreatment of feedstock and control of ancilary fly breeding sites. Further, nematodes are a cure, not a means of prevention. Once the flies are brought under control the nematode numbers typically decline in response until their numbers disappear entirely. These microscopic worms cannot be effectively cultured in a worm bin indefinitely unless the system is continually innoculated with fruit flies, which, of course, sort of defeats the purpose of introducing the nematodes in the first place...

Pyrethrin is a safe, organic insecticide that can be sprayed in the worm bin to control flies. It, too, should be used in conjunction with pretreatment of feedstock, and discontinued once the flies are brought under control (long term use has not been studied in worm bins and there is some concern over negative impact to some of the beneficial insects associated with a healthy worm system).

Prevention is the key to controlling fruit flies and fungus gnats in indoor systems. In outdoor bins, however, where the passing fruit fly or gnat can and does smell the wonderful bin environment, efforts at controlling them is essentially useless, and, in fact, is non-beneficial. Fruit fly larvae are voracious decomposers that aid the system in processing organic waste materials while posing no threat to you, your pets or your garden plants. Indoors they are a nuisance, landing in your coffee and merlot, but outdoors, they are another beneficial bin resident that can be allowed to flourish in the bin as nature intended.

So, to recap; pretreat feedstocks prior to feeding indoor bins by either microwaving until bubbly and hot, or freezing for roughly three days; use beneficial nematodes or pyrethrin to control fruit fly infestations.

Make sense?


    Bookmark   December 12, 2005 at 11:16AM
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newbie314(Z9 CA)

Thanks for the info.
Yeah I figured the trap inside the bin was of no use.
The bin is outside. Won't be let in. So I'll only control the flies by putting no-see-um screen on the bin.

So two more questions:
Aren't the flies harmful once flying around and trying to eat our food (disease).

Second: I live in the central valley and tell me how my bin can survive the heat in the summer. Under the shade underneath my citrus tree in the back corner (very little evening sun).
Maybe shiny emergency blanket to reflect the sun, and small water drip everyday.
Would this be good enough.

Need to prepare.

    Bookmark   December 12, 2005 at 7:35PM
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Kelly_Slocum(sw WA state)

"Aren't the flies harmful once flying around and trying to eat our food (disease)."

Fruit flies are not disease vectors in our part of the world, thus, no, they are not a significant health threat. They are, however, a significant nuisance, and that's good enough for me!

"I live in the central valley and tell me how my bin can survive the heat in the summer. Under the shade underneath my citrus tree in the back corner (very little evening sun)."

Worms are routinely kept outdoors in southern California, Arizona, New Mexico, and Texas with no measurable problems from the heat. Kept in the shade and always damp, evaporation of moisture from the bin is more than adequate to keep the worms cool when the temperature soars above 100F. Keeping the bin consistently moist is generally the challenge, but can be addressed by installing a small drip irrigation system in the bin, or coming up with some other creative idea for an ongoing source of moisture. Many folks in your part of the US, just to be certain the worms will be comfy in the heat, bury bottles of frozen water in the bedding to provide cool zones. Your idea of using an emergency blanket to reflect heat away from the bin is also worth trying.

Outdoor vermicomposting is more commonly practiced than you may realize, even in the baking heat of southern California. You are likely to find this much less of a problem than previously thought.


    Bookmark   December 13, 2005 at 1:36PM
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newbie314(Z9 CA)

Water will be no issue since I have a drip system that also goes to the citrus tree.

I am thinking of a fan. I have some spare solar cells from my solar lanterns (got replaced by the company a while back). One has been converted to a battery charger (had 4 extra NiMH why not, lanterns do charge batteries).

Maybe the other one can be used to drive a small 3V or less fan on the lid. Wet inside, fan on the top, could be interesting.

As for winter, I'm thinking of making a mini-greenhouse enclosure around it (use the wood that was used for the bench when the bin was indoors :-( ). Only concern is not to fry them when the heat picks up.

I heard someone mention use a wheat germ sock?? to help warm the bin or compost. Is this recommended. I have used Wheat germ before and boy does it get hot. I was thinking of packing a toilet paper role with wheat germ and newspaper (so it's not too anaerobic). Does this sound like a plan. The worms have plenty of space to hide in the bin (stacked OSRC JR).

Oh Kelly, we had quick conversation on the stacking etc. Well definitely see some issues with my OSCR JR. Big issue is the weight of the top bin compressing unfinished items in the lower bin like newspaper. Thinking some shims on the side may help such that the bin sits nicely on the bottoms unfinished compost, then lower it slower as the bottom bin becomes more finished. I know the easiest would be to split the bin. Since they are outside I might do that, but in the spring when the weather is better. Right now the worms are hiding in the lower bin (a little warmer now).

    Bookmark   December 13, 2005 at 3:05PM
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I have the same problem with the flies, have been running the indoor bin since July, and am building a no-see-ums bag to keep the buggers in there and hopefully vacuum them up when I open the bag when it's feeding time, once a week. I do like the idea of nematodes and will look for Montreal local distribution and the variety required to take care of the gnats. Currently I collect my "food" in an old icecream container and feed once per week. I think I'll let the container sit in the freezer for a few days then let it thaw and get soupy for the worms. Fortunately I am single so I can have the bin wherever I choose, however, the visitors to my place look a bit perplexed when they see the flies all over the place. I vacuum about once a day to pick em up. Any other suggestions? I can't wait to get the outdoor compost going. It'll be another project as I don't have that outdoors yet. I won't worry about the flies there!

    Bookmark   January 18, 2008 at 1:42PM
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Welcome to the forum. I recently had a fruit fly infestation and got rid of them through several approaches.
I converted an old jam jar to a fruit fly trap by puncturing the cover with a nail and added a little left over red wine to the jar. This along with stopping any feeding to the my bins for a couple of weeks and vacuuming up any stray fruit flies that couldn't find their way to the party in the ff trap;)

mataka4 (Montreal)

    Bookmark   January 18, 2008 at 3:55PM
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Hello-we've just encountered these fungus flies and have been following your suggestions here-we purchased the pyrethrin (?) spray. We've covered the compost in a heavy layer of fresh bedding and I just pulled it aside to spray the inside of the bin (bottom, middle, etc.). Now-how often and how much do we do this? We don't want to kill our worms!

Also-for anyone who wants to answer-i think it'll soon be time to split our bins as the worms seem to be multiplying fast-suggestions on what to do with the extra half? should we just start a second bin? are there places that will take extra worms? thoughts?

    Bookmark   August 2, 2008 at 6:36PM
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leearnold(z5 In.)

I have had good luck keeping the fruit flies under control with a bowl of water. Yes, water. Put about a cup into a bowl and add a drop of liquid dish soap. That breaks the water's surface tension. And when the flies land to get a drink, they fall in and drown. Try it. You'll be surprised.

    Bookmark   August 2, 2008 at 8:45PM
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napapen(ca 15)

My bins are outside and small frogs take care of the fruit fly problems when I have them.


    Bookmark   August 2, 2008 at 11:39PM
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squeeze(z8 BC)

something folks should keep in mind is that fruit flies and fungus gnats, like dozens of other critters, are part of the community of decomposer organisms that may be present anywhere there is decaying organic material ... you may be able to get rid of them *for now*, and if you manage your worm bin is just the right way, you may be able to avoid most "pest" organisms, but .... there is no magical solution to keeping them all away all the time, and as Kelly pointed out above, care with the feedstock is the key to avoiding the main problems


    Bookmark   August 3, 2008 at 12:14AM
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scripsee, as far as dividing your worms, by all means start a second bin. If you really don't want 2 bins, or don't have enough food to sustain more than 1, either give some worms to your neighbours or friends so they can learn how to vermicompost.
You can also post them on Craigslist or FreeCycle, as well.

Good luck with the FF, Fungas gnat problem. It will get better, perseverance and prevention goes a long way.
FYI, I ALWAYS freeze all of my food, prior to feeding.


    Bookmark   August 3, 2008 at 8:15AM
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I had such an infestation in early spring, that I just set my worm farm outside. The flies never left the bin. I kept feeding the worms, but after a few months they weren't looking so good. I figured if I could separate the worms manually and rinse them off in water, I could bring them back inside.
I dumped the whole worm farm on the grass and separated them. I washed out the bin, put new bedding in and skipped the rinsing part. Back inside with no flies.
For the first months I was good about freezing the banana peels (their primary food). Then I started getting lazy and bam, fruit flies everywhere.
I will be more careful this time!

    Bookmark   August 8, 2008 at 11:12PM
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