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Managing Kitchen Fruit Flies with a Little Shop of Horrors

367 points| zacharycohn | 2 years ago |blog.zaccohn.com

166 comments

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[+] Jaygles|2 years ago|reply
I am convinced fruit flies are some sort of multidimensional being. I will sit in a room, observe three fruit flies in the air, swat and kill those three fruit flies, then sit back and observe no change in the number of flies in the air.

They either throw out decoys when you swat them to fool us, or there’s a large queue of them waiting to take their turn to keep the number flying constant

[+] phito|2 years ago|reply
I've been growing carnivorous plants for more than 15 years and own a business selling them. I can assure you these Sarracenia will not do anything against your fruit flies problem. Pinguicula or Drosera will catch more of them and can actually grow indoors all year round given enough light. But even then, they're not really good at pest control.

Sarracenia are outdoors plants, they need a ton of direct sunlight and a seasonal rest in winter. They already look light deprived in your pictures.

[+] danparsonson|2 years ago|reply
Came here to say this - pings and sundews are a better choice; loads of sticky leaves just begging to be landed on. An Alice Sundew (Drosera Aliciae) makes a fine pet and is easy to care for.
[+] zacharycohn|2 years ago|reply
/shrug I got 15 dead fruit flies in my Sarracenia. YMMV I guess.
[+] phyzome|2 years ago|reply
"these Sarracenia will not do anything against your fruit flies problem" seems directly contradicted by the blog post. Perhaps some unexpected environmental difference vs. your setup?
[+] Loughla|2 years ago|reply
I've always been fascinated by carnivorous plants, but have a black thumb. Do you have suggestions for "easier"to care for options indoors?
[+] EB66|2 years ago|reply
For anyone contending with the menace of fruit flies or gnats (and especially if you own a fair number of indoor plants), I could not recommend these more wholeheartedly:

https://www.amazon.com/Stingmon-Pack-Sticky-Fruit-Fungus/dp/...

It's essentially a better looking version of fly paper. They're easy to place alongside indoor plants. Fruit flies and gnats are attracted to decaying organic matter and the moist soil of indoor plants is an often overlooked oasis for them. Gnats are more likely to hang out in indoor potted soils (especially if overwatered) because they feed on fungus, but fruit flies can take refuge there too.

A couple years back I had a months long battle with fruit flies. Kitchen was always clean, garage sealed up tight, no indoor compost, I used apple vinegar traps of all styles but nothing solved the problem until I placed those sticky paper inserts at the base of all my indoor plants. Within a week the fruit flies were gone.

[+] adriand|2 years ago|reply
The best method is to put a bit of fruit peel and some beer or wine or vinegar at the bottom of a glass (e.g. a pint glass) and then fashion a cone out of paper, where the wide end of the cone is the same size as the mouth of the glass. Cut the pointy end so it’s a few millimeters wide. Insert pointy end first, and tape the wide end of the cone to the brim of the glass, forming a seal. Flies will enter the glass via the opening in the point of the cone, and will be unable to leave. This will collect huge numbers of them with zero maintenance.
[+] johnyzee|2 years ago|reply
As described in the sibling comment, a glass with a fifth of vinegar, same amount of water, and a drop of dish soap will do the trick fine. No craftsmanship needed. The flies drop instantly when they touch the liquid.

Most people cover the glass with some cling film and punch a few holes through, but it will work fine without. The main advantage of the film is that the liquid won't evaporate away, and the trap will be good for a couple of weeks.

[+] aradox66|2 years ago|reply
This is awesome and you feel powerful vengeance until you accidentally slip the paper cone a bit on disposal and a hundred fruit flies escape at once.
[+] Fnoord|2 years ago|reply
Yes, I can confirm this works very well. Best, I don't know the alternatives; this one works though.

I saw the other day on Thingiverse a fruit fly trap. Example: [1] (it wasn't this one, and there are many other ones, but this one resembles the looks of the paper version). But I think its OK to make such a trap a few times a year during summer (when they're abundant here). You also wanna get rid of them ASAP, as they attract bigger flies.

[1] https://www.thingiverse.com/thing:3032998

[+] zacharycohn|2 years ago|reply
I've tried this several times and it's never been successful. I don't know what I'm doing wrong, but I'm glad you got it to work!
[+] unixfg|2 years ago|reply
Buying a plant seems easier, and I'm definitely not crafty enough to build a fruit-peel beer cone glass and have it look good enough to display.
[+] cudgy|2 years ago|reply
Yes, they love a little wine in a glass wine just like many humans. I never had to fashion a funnel, but it sounds like a nice trap.
[+] MandieD|2 years ago|reply
A CD makes a good template for this cone, and cereal boxes are just the right weight/flexibility.
[+] NoZebra120vClip|2 years ago|reply
Time flies like an arrow. Fruit flies like a banana.

When I was a child, I liked lizards, rats, and frogs as pets, and I also enjoyed the occasional Venus Flytrap from the nursery. I considered some pitcher plants recently, but I had to weigh their effectiveness against cockroaches, and the need to build a whole tropical environment with lights, heat and humidity.

Lastly, that brand of essential oil is the same one I purchase, and it's great. I use them in a diffuser.

[+] zacharycohn|2 years ago|reply
Pitcher plants don't need a tropical environment! There are many that are even from Canada. Ours is doing great in an indoor Seattle environment just sitting on a windowsill that only gets an hour or two of direct sun per day.
[+] Loughla|2 years ago|reply
I'm pretty sure there are pitcher plants in my woods in the Midwest US. I can't imagine they need tropical environs.
[+] Order|2 years ago|reply
Love this Groucho Marx quote - just read it recently in Consciousness and the Brain (Dehaene)
[+] staplung|2 years ago|reply
Everyone knows that fruit flies spontaneously generate.

My preferred method to get rid of them is with a black hole: I put a couple of pieces of fruit into my homemade Superconducting Apricot Collider, set it on high and then place the resulting black hole right above the compost bin. Works every time. Just be careful with the black hole because if you drop them they fall all the way to the center of the earth and are rather difficult to retrieve.

[+] dylan604|2 years ago|reply
You can control your black hole with rare earth magnets. set them around the area where you are going to create the black hole to form a containment area. you might need to play with the size/quantity/distance of the placement of the magnets for best performance. I have not needed dry ice for cryogenic cooling.
[+] latchkey|2 years ago|reply
Fungus gnats are also an issue if you keep indoor plants.

I recently discovered that you can water your plants with mosquito dunks in the water, which will put the bacteria (aka: BTI, bacillus thuringiensis strain BMP 144) contained in the dunks into the soil. The bacteria then paralyze the larvae growing in the soil and they die.

Doing even more research, it seems there is a newer strain of the bacteria (AM 65-52) that you can buy in 16lbs! buckets for $570 off Amazon (or people have broken it into smaller batches on ebay).

This stuff really works like magic. Once the adults die off, no more appear.

Gnatrol Biological Larvicide Fungus Larvae

[+] hahajk|2 years ago|reply
I remember reading that fungus gnats are a sign you're overwatering your houseplants. (Water uptake is correlated with photosynthesis, indoor plants don't get or usually need much light). I just did a quick internet search and it looks like the popular advice for fungus gnats is still the same - water less. It'll also prevent root rot.
[+] javajosh|2 years ago|reply
I have to say that excitedly waiting for Amazon to deliver 16 lbs of bacteria makes me want to laugh/puke/write a screenplay for black mirror.
[+] sshanky|2 years ago|reply
This definitely works for me. One of my favorite solutions. I used to have a bottle of concentrated bacteria but I don’t know where to find that any more. Now I get something called mosquito bits and let them soak in the water I use on the plants.
[+] the_af|2 years ago|reply
I know the author, quite correctly, rules Venus flytraps out, but for the sake of argument:

I used to keep some just for the sake of it, not at all to hunt bugs because that won't scale. In humid Buenos Aires, I tried both indoors and outdoors and... they are pretty hard to keep, aren't they?

You must water them lightly with distilled water. You must NOT let them flower (it's hard to overstate this, but it's true and I verified it first hand: the plant sprouts a single flower once a year, and if you don't prevent this by cutting the stalk ASAP, a single ugly white flower will sprout, and then your flytrap will die of exertion). You must not overfeed it. If it catches a bug on its own, chances are the "trap" will turn black and rot.

They seem to be very hard to keep outside their natural swamp environment...

[+] a_bonobo|2 years ago|reply
>They seem to be very hard to keep outside their natural swamp environment...

As the NatureServe status says:

>The Venus Flytrap, a carnivorous species, is a narrow endemic of the coastal plain of North and South Carolina in the southeastern United States. It has very strict habitat requirements which include frequent natural fire, an open understory and low nutrient soils. There are close to 100 extant natural occurrences and between 73,000 - 158,000 total individuals. The species continues to decline, however, and should be reviewed frequently. Threats include poaching from wild populations, habitat conversion, and fire suppression.

There are very few natural areas left where these plants can survive, and these areas are tiny!

>Current range: The range of Venus flytrap is quite localized in scattered savannas of the coastal plain of southeastern North Carolina and adjacent eastern South Carolina in an approximate landward radius of 100 miles around Wilmington, North Carolina (North Carolina Natural Heritage Program 2010). Currently 68 extant occurrences are known from the following counties in North Carolina (the number of occurrences in parentheses): Bladen (5), Brunswick (21), Carteret (1), Columbus (3), Craven (1), Cumberland (4), Hoke (7), New Hanover (5), Onslow (12), Pender (7), and Sampson (2) (North Carolina Natural Heritage Program 2010), and Horry County (4), South Carolina (South Carolina Heritage Trust 1993b).

In a way, these plants have evolved into a dead end. They mostly lost their chloroplast genomes so they can't 'go back' to being regular plants.

Perhaps your mistake was that you don't set your kitchen on fire often enough?

https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.1597...

[+] dylan604|2 years ago|reply
I've only seen carnivorous plants do well in terrariums. Trying to keep them as a house plant doesn't work since most houses are not humid jungle climates inside. even orchids do not do well in most people's homes. The best orchids I've seen were kept in a bathroom with a window steamy showers are taken daily.
[+] nullwarp|2 years ago|reply
My favorite way to tackle this is to use a bowl of bait and one of those cheapo bug zapper rackets.

I take the racket and use a rubber band around the button to keep it "on" and then set the racket above a bowl of whatever bait I need to use.

I leave it there until the zaps finally stop.

Has yet to fail me in clearing out a fly infestation.

[+] TimBurman|2 years ago|reply
5% acetic acid vinegar, a squirt of lemon dish soap and a few tablespoons of sugar mixed together in a bowl kills the fruit flies within a day of arrival. It will evaporate over time but adding water back to the original level reconstitutes the trap and it will work for months. This is just an interim solution until the lasers and machine vision are working.
[+] AlbertCory|2 years ago|reply
Depends on your home's location, I guess. I don't have fruit flies.

Where I am, pantry moths are the problem. One of the few genuinely useful ideas I've ever gotten off NextDoor is this: Dr. Killigan's Premium Pantry Moth Traps with Pheromones.

The pheromones attract the moths, and the glue makes them stick to it and die. You can put it out of site in a cabinet, and after a few weeks it's covered with dead moths.

[+] arijun|2 years ago|reply
You can also mitigate pantry moths by rotating all their potential food sources (like flour) through the freezer for a few days to kill any eggs and larvae that might be there. If I see a moth I will try to hunt down which food it came from (you can sort of identify by seeing webbing which suspends bits of whatever they’re eating), and toss it. And then everything else goes in the freezer to stop it from propagating.

The other option is to put things individually into well-sealed tubs or jars, to isolate any moths that might be there (they will drill a hole through thin plastic, like ziplock)

Honestly the trap method makes me a bit squeamish; if you’re continuously catching new moths, that means there're still eggs and larvae in at least one of your bags of food. The idea of eating that is a bit disturbing is to me.

[+] UberFly|2 years ago|reply
He mentions apple cider vinegar and dish soap. It's worked well for me too but there are always a few flies that aren't as interested in the concoction so yea only a 90% solution. I've also found that many of these flies come in from the grocery store in things like strawberries so we're careful to check before they enter. Good article - would love to try these plants.
[+] mcv|2 years ago|reply
I'm afraid I take a much cruder approach. We have a fruit fly infestation every summer, and besides keeping fruit and other food out of their reach, I simply hunt them down. Nearly every summer our walls are a graveyard of hundreds of drosophila corpses. (Though I haven't seen many of them yet this summer.)

Unfortunately they leave ugly spots on our walls and ceilings, and most walls are not that easy to clean, so I developed a couple of techniques where I don't squash them on the wall: I slap my hands together just above where they're sitting, they see my hands move and fly up, just between my hands. Timing takes some practice, but I've had thousands of opportunities to perfect this technique.

Our kitchen wall has been treated to make it easy to clean, so there I just squash them against the wall, which is much easier.

[+] mst|2 years ago|reply
Huh. I wonder if other sorts of fly are amenable to the clapping trick.

I shall have to experiment.

[+] ornornor|2 years ago|reply
This is how we won our war on fruit flies:

- repot all plants after rinsing all soil from them

- use leca balls instead of soil and water the plants with a water + fertilizer solution (this is what they do for office plants and why they have stickers saying “do not water”)

- all incoming fruits and vegetables soak in water + vinegar for 20–30 min as this kills any eggs (they’ll also last longer because they don’t spoil as fast)

- have bug screens on any window that we keep open (they don’t come standard in Europe)

- the fruit basket is also enclosed in a bug screen for good measure

I believe fruit flies mostly came through grocery store fruits (eggs on the fruits) and then hatched and went to live in the houseplants soil where they’d eat the roots.

[+] ortusdux|2 years ago|reply
I have some very happy pitcher plants in the window over my sink for just this reason. I've been meaning to pick up some Triantha occidentalis as well, a newly discovered carnivorous plant. Well the plant is not newly discovered, but it took doping fruit flies with N-15 and monitoring nutrient uptake to prove that it is metabolizing insects.

https://www.pnas.org/doi/full/10.1073/pnas.2022724118

[+] CatAtHeart|2 years ago|reply
We bought a cheap standalone bug zapper and put it on the counter and it has been a life saver for the fruit flies. Ours come from bananas, we think, and washing them after bringing them home from from the store seems to help some too.

The best part is, working from our offices in separate rooms, my wife and I will hear a zap and both shout "Good job bug zapper!"

[+] assimpleaspossi|2 years ago|reply
I had a fruit fly (or some kind of fly) issue a while back. Couldn't figure out where they were coming from or why. For some reason, I pulled the rubber ring out from my kitchen sink's garbage disposal. It was the nastiest thing, covered in goop. Cleaning that and the area in the disposal it sat in solved the problem.
[+] at_a_remove|2 years ago|reply
I occasionally get drain flies in the shower, but this time I have a Spider In Residence. I previously had a pretty good working relationship with a shower spider: I would do a series of thumps to indicate I was about to turn on the shower. I would leave a couple of drops of water on the shower insert's top edge. I would fling various bugs into its web. We had a basic understanding. It died, sadly.

The new Shower Spider is doing alright, and it occurs to me that there's this complex web of life: my hair in the drain, some kind of fungus is in there growing on it, drain flies eating the fungus and flying up, they are caught by the spider, which then makes a web to catch more flies. So the matter that was once my hair enters the cycle of life and ends up above me in a spider web.

[+] elliottkember|2 years ago|reply
If none of the low-tech hacks in here seem to work, or you have the same kind of gadget addiction as me, I can recommend the "Katchy" brand of bug catchers. They work at night with UV light, and have decimated the fruit fly population in my kitchen.