Does fly spray kill fruit flies? Yes, the ones it hits
A fly spray kills every fruit fly it hits. It does nothing to the eggs and larvae in the fruit, which are the next lot of flies, and the fruit bowl is the one place a typical label says not to spray. Here is where spray actually fits.
By The Pest GuyLast updated
The short answer
Yes, fly spray kills fruit flies. Only the ones it hits, and none of the ones on the way.
Any household fly spray will drop a fruit fly. The trouble is everything the spray never touches. Fruit flies lay their eggs near the surface of overripe fruit, and the larvae feed in it for five to six days. Iowa State University Extension puts it plainly: a spray gets rid of the adults present when you spray, and that is "only a temporary relief at best".
So you spray, the room is clear, and a few days later they are back. Nothing came in. The next lot hatched out of the banana.
The order that works is the other way round. Find what they are breeding in and bin it. Then deal with the adults still flying, with a spray if you like, or with a trap by the fruit bowl, which carries on catching while you get on with your day. If you cannot find the source, the places fruit flies breed in a house go well beyond the fruit bowl.
Three sprays and the bin, and what each one reaches
The adults are the part you can see. The eggs and larvae are the part that decides whether they come back.
| Option | The adults | The eggs and larvae | Near the fruit bowl |
|---|---|---|---|
| Aerosol fly spray | Kills the ones in the air when you spray. Temporary relief at best. | Nothing. The problem continues however often you spray the adults. | A typical label: remove or cover food and utensils, keep the spray 1 metre from surfaces. |
| Soapy water spray | Only the ones it soaks. Contact only, nothing left once it dries. | Nothing it does not soak, and it does not reach inside the fruit. | Aim it at the fly. Many household soaps are poor insecticides anyway. |
| Vinegar spray | Draws them in. Cider vinegar is the bait extension services put in a trap. | Nothing. | It puts their favourite smell on the worktop. |
| Binning the source | Leaves the ones already flying. That is what a trap is for. | Removes them. Sometimes one overripe banana is the whole problem. | Nothing sprayed. Fruit in the fridge before it starts to ferment. |
Sources: University of Kentucky Entomology (ENTFACT-621); Iowa State University Extension; University of Rhode Island "Vinegar & Fruit Flies" factsheet; University of California Cooperative Extension, "Soap Sprays as Insecticides"; a UK fly and wasp killer safety data sheet (SC Johnson, revision 2014). The label wording is one product's; the label on your own tin is the one that applies.
Why they are back the morning after you spray
It is a numbers problem, and the numbers are all on the side of the fruit bowl.
A female fruit fly lays about 500 eggs, one at a time, near the surface of moist, fermenting food. The University of Rhode Island factsheet lists the usual places: overripe fruit, rotten vegetables, dirty bins and the slime in drains. The eggs hatch in 24 to 30 hours. The larvae feed on the yeast in the fermenting fruit for five to six days, then crawl somewhere drier to pupate. New adults are ready to breed in about two days. The whole cycle runs 8 to 15 days, depending on how warm it is.
Lay a spray over that and see what it touches. It kills the adults in the air. It does not reach a single egg on the skin of a peach or a larva inside a split banana. The fruit fly larvae are where the next week of flies is coming from, and no aerosol is getting to them.
The University of Kentucky's entomologists sum it up in one line: unless the breeding sites are removed or cleaned, "the problem will continue no matter how often insecticides are applied to control the adults." That is why a can of fly spray feels like it works and then doesn't. It did work. It just worked on the wrong generation. If you want the day-by-day version, how long fruit flies live walks through it.
Spraying near food: what the tin actually says
Fruit flies gather on the food. A typical fly spray label says to get the food out of the way first.
Here is the awkward bit. The flies are sitting on your fruit bowl, your bread bin and your chopping board. And the label on a standard UK fly and wasp killer says, word for word: "Remove or cover food, food preparation equipment and eating utensils."
The same label goes further. It says to keep the spray at least 1 metre away from all surfaces and walls, to use it only in a well-ventilated room, and not to breathe the spray. It says to remove or cover fish tanks and animal cages, and to turn off an aquarium's air filter while you spray. It also carries the warning that it is toxic to aquatic life with long-lasting effects.
Put those together and fly spray in a kitchen looks like this. Take the fruit, bread and anything open off the side, or cover it. Cover the fish tank. Spray into the air, a metre clear of the worktop, never at the bowl. Open a window. That is a lot of fuss for a room of flies that will be replaced within days, which is the real case for doing the source first and keeping the spray for what is left.
Every product's label is a bit different, so read the one on yours and follow it. One more thing on buying: HSE's rule is that a biocidal product must be authorised before it can be supplied in Great Britain, so buy a household fly spray sold here, with its directions on the tin, rather than something shipped in with a label written for somewhere else.
Homemade sprays to kill fruit flies
Soapy water and vinegar are the two recipes that come up. One works on contact only. The other is bait.
Soapy water. A University of California extension note on soap sprays sets out the limit. Soap works strictly on contact, with no residual effect, so the spray has to hit and cover the insect to do anything. Once it dries it is doing nothing at all. The same note warns that many soaps and detergents are poor insecticides to begin with. So a soapy spray bottle will drop the odd fly you get a clean shot at, and that is the honest ceiling. Aim it at the fly, never at the fruit you are about to eat.
Vinegar. This one backfires. Cider vinegar is the bait university extension services use in a fruit fly trap, and the Rhode Island factsheet lists vinegar alongside cider, wine and juice as things they hover around. Spray it on the worktop and you have put their favourite smell out in the open with nothing to stop them leaving. Vinegar works when it is inside something, which is the whole idea behind apple cider vinegar for fruit flies.
If what you really want is a smell that keeps them off, that is a different question from killing them, and whether a fruit fly repellent works gets its own answer. And if the tiny flies are round a plant pot rather than the fruit, check fruit flies or fungus gnats before you buy anything, because the fix is different.
What to do instead, in order
Three steps. The spray is allowed in step three, if you still want it.
1. Bin the source. The Rhode Island factsheet is blunt about how small the fix can be: sometimes getting rid of one overripe banana, a jar of something fermenting, or a dirty bin is enough to control them. Check the fruit bowl, the food caddy, the recycling (unrinsed bottles and cans count) and the drain. Kentucky adds mops and cleaning rags, because all they need is a moist film of fermenting material.
2. Put the fruit in the fridge. The same factsheet says to refrigerate fruit and veg you are not eating straight away, before it starts to ferment. That takes away the next place to lay.
3. Deal with the adults still flying. This is where spray has an honest place. The University of Georgia's advice is that once the source is gone, a pyrethrum-based aerosol can kill the adults left in the room, following the label. The other option is a trap by the fruit bowl, which needs no food moved, no window open, and keeps catching the stragglers as they turn up. Everything that makes a trap catch flies and keep them is in the fruit fly trap guide, and the homemade fruit fly trap page covers the jar version.
If what you have is a sudden cloud of bigger flies rather than a few fruit flies, that is a different problem with a different source, and flies in the house covers it.
For step three, a trap does the spray's job without moving the food
Once the source is in the bin, this mops up the fruit flies still flying. It can sit right beside the fruit, where a spray can't go. It catches adults. It does nothing to a banana that is still breeding them, so bin that first.
What I’d use
Reusable cider vinegar trap
Escape-proof fruit fly trap
A two-part cup and lid you fill with about 25 ml of cider vinegar and stand by the fruit bowl.
Eight slots in the lid feed a funnel that drops flies through one 4 mm hole into the dark middle of the cup. The brightest points a trapped fly can see are pinholes too small to get through, set away from the real exit, so the way out is the place they are least likely to look.
- Ways in
- Eight slots in the lid, into one funnel
- Way out
- One 4 mm hole, under the solid centre of the lid
- Holds
- About 25 ml of vinegar, to the moulded fill line
- Size
- 6.7 cm across, 5.4 cm tall
- Refills
- None to buy. It runs on cider vinegar from the cupboard
Watch out for
- Vinegar and washing-up liquid not included.
- Made for fruit flies. Flies from a plant pot or drain need the source found.
- Tip, rinse by hand and refill once it fills up.
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No brand pays for a mention here, and nothing on this page earns me a commission. The card above links out to a shop, and I get the same whether you buy or ignore it. The link is there because finding the thing is the boring half of acting on advice, which is also why the watch-outs sit on the same card as the reasons to buy.
About this resource
The weight on this page is carried by university extension sources: the University of Kentucky's fruit fly factsheet, Iowa State and Georgia extension, the University of Rhode Island's vinegar and fruit fly factsheet, and a University of California note on soap sprays. The label wording comes from the safety data sheet for a UK fly and wasp killer (SC Johnson, revision 2014), and the point on buying from HSE's biocides guidance.
The honest limit is the label. One product's precautions stand in here for a typical fly spray, and yours may word them differently, so the tin in your hand is the one to follow.
Common questions
What spray kills fruit flies immediately?
Any household fly spray will kill the fruit flies it actually hits, straight away. Iowa State University Extension calls that "only a temporary relief at best", because it does nothing to the eggs and larvae already in the fruit. Those are the next lot of flies, so the kitchen fills up again. Bin the source first, then deal with the stragglers.
Will spraying vinegar get rid of fruit flies?
No. It does the opposite. Cider vinegar is the bait university extension services put in a fruit fly trap, so spraying it on a worktop puts their favourite smell out in the open. Vinegar belongs inside a trap they cannot get back out of.
What is the best homemade fruit fly killer?
A trap, rather than a spray. The University of Kentucky's version is a jar of cider vinegar with a paper funnel in the top, stood wherever the flies are. A soapy water spray only kills the flies it soaks and leaves nothing behind once it dries, so it is a lot of work for the handful you can hit.
How to get rid of fruit flies in 2 minutes?
You can kill the ones in the air in two minutes with a spray, and that is all you can do in two minutes. The eggs are laid near the surface of overripe fruit and the larvae feed there for five to six days. The fastest real fix is the bin: take out whatever has started to ferment, and the next generation goes with it.
What kills fruit flies in the house overnight?
A cider vinegar trap left by the fruit bowl overnight catches adults while you sleep, and that is the honest overnight win. Nothing overnight touches the eggs and larvae in the fruit itself. If they are back in the morning, something is still breeding, and the job is finding it.
How long does a fruit fly infestation last?
As long as the thing they are breeding in. The University of Rhode Island factsheet puts the life cycle at 8 to 15 days depending on temperature, with each female laying about 500 eggs. Remove the source and you are waiting out the adults already flying. Leave it and every spray only clears the room until the next adults come out.