Put a drop of soap in the vinegar
Many discussions trap fruit flies with cider vinegar and a drop of washing-up liquid. Why the soap matters, and why the flies keep coming.
Built from people with a cloud of small flies over the fruit bowl and a kitchen they had already cleaned.
There is a small cloud of flies over the fruit bowl, another over the sink, and they lift and settle every time a hand goes near; you have cleaned the kitchen twice and they are still here. People are the source here.
Trap them with cider vinegar and one drop of washing-up liquid in an open cup, because the soap is what makes the trap work.
Then find the thing they are breeding in and throw it out, because the source is what makes it end.
The trap, and the part people miss
Many people make the same trap: a cup of cider vinegar with a drop of washing-up liquid in it. Many people explain the part that the cup of plain vinegar on your counter is missing: the vinegar draws the flies, but they can stand on its surface, and the soap breaks that surface so that a fly landing to drink goes under. Many people corrected the person who first shared the trap, who joked that the soap demoralised the flies; it does not, and the physics is why an unsoaped cup catches nothing. Some people add a lid — cling film stretched over the cup with a few holes poked in it — so that a fly which gets in cannot find the way out; one person uses a paper cone in a jar and says it beat the open cup by a distance, and one person warns the film has to seal to the rim. Many people say the bait can be anything sweet and fermenting — wine gone sour, beer, juice, a piece of soft banana — and people’s preferences among vinegars are in the first question below, along with the conversations that swear by an open bottle of cheap fortified wine.
Why they keep coming
Some people say the thing that changes the fight: the flies are not coming in from outside, they are hatching from something in the room. Fruit flies lay in ripe fruit and in rot, and one person says the cloud that appeared overnight was born there. Some people warn that a trap kills adults and does nothing to eggs, and some people say the first job is finding the breeding place — the bananas, the bin, the drain, the waste disposal — and getting it out of the house. Some people say the drain, with boiling water and a clean. And one person points out something that may end the search: flies living in the drain itself are a different insect altogether, drain flies, which want a cleaned drain and ignore vinegar; and flies rising from a houseplant’s soil are fungus gnats, another insect again, which the trap will not catch. The second question below carries the argument about washing fruit, the shared-flat problem, and what to do when the trap catches nothing.
The other methods
Some discussions vacuum them off the walls, and some people prefer a flame for speed, some the vacuum for ease. Some people gather the flies on the one lit lamp in a dark room and take them with a candle; people argue whether a pan of simmering vinegar kills them or only stings your eyes, and some people warn not to fill a home with vinegar fumes if a bird or a small animal lives in it. The third question below carries all of it; none of it is the counsel, because a soaped cup by the fruit bowl and an emptied bin need no flame and no fumes.
If there is a bird or a small mammal in the house, the simmering is out; the cup makes no fumes, and people name pet safety beyond that as a gap. If your flies are hairy and scuttle rather than fly, or rise from a plant pot, the trap is the wrong tool and the second question says which insect you have. If they ignore the vinegar altogether, they may be house flies, and the linked page on where to aim the swatter is yours. And if the kitchen is shared, one person says eradication is hard unless every flatmate agrees to the cleaning.
Common questions
It caught a few and the rest are still here. What am I doing wrong?
Two things, people say, and neither is the trap. First, the bait: some people say red-wine vinegar does not draw them and cider vinegar does; individual people swear by malt vinegar, balsamic, a layer of red wine on top of the vinegar to hide the soap smell, beer, sugar water, or a piece of over-ripe banana, and people argue, one person each way, malt against cider and balsamic against cider, which is to say the flies have preferences and people do not agree what they are. Many people say the principle under all of them is that the flies come to anything sweet and fermenting, and some people say an open bottle of cheap sweet fortified wine cleared a whole flat overnight — with some people objecting that the flat in question had not been cleaned, and one person’s note that other wines may not do the same. Second, the door: one person says the soap is what stops a fly standing on the surface of the vinegar and walking off; one person warns the film has to be sealed to the rim or they will not go in; one person uses a paper cone in a jar instead of film and found it caught far more than an open cup; one person baits a zip-seal bag with fruit scraps, leaves a small hole, and once the flies are in seals it and throws the whole bag away. One person warns a trap is also an advertisement — it can draw flies in from elsewhere in the house — which is why it goes where the flies already are. How long a trap keeps working and how to empty one are asked and not answered.
Where are they coming from? I have cleaned the kitchen twice.
From inside the house, some people say, not from the window: a fruit fly lays eggs on the fruit or in the rot, and the cloud that appeared overnight hatched, one person says, rather than arrived. Some people say removing the breeding place comes first — the ripe bananas, the bin, the drain, the waste disposal, the dishes — and one person puts it as source first, trap second; some people warn that traps kill the adults and do nothing for the eggs, and some people warn that traps alone do not solve it while breeding grounds remain, so a clean kitchen with a trap in it is the only version that ends. One person says new eggs arrive on the produce itself, bananas especially, and people argue whether washing fruit when you bring it home stops them — some people say it removes the eggs, one person says the life cycle would show larvae in the fruit if that were where they bred, and this page does not settle it. Some people say the drain: pour boiling water down it and clean it out, and one person pours bleach, which this page carries as one person’s. Then the point that changes the diagnosis: one person points out flies living in the sink drain are drain flies — hairy, and they scuttle rather than fly well — not fruit flies, and they want a cleaned drain, not a vinegar cup; one person says flies rising from the soil of a houseplant are fungus gnats, which want the soil drenched with soapy water or oil and are not caught by the trap, and one person points out the yellow sticky cards sold for them count the population and do little to lower it. If the trap catches nothing after a night, one person warns look again at what the insect is. One person in a shared flat says nothing works unless the whole household is doing the same thing, and one person objects that an infestation with a hidden nest cannot be ended until the nest is found.
What about the vacuum, the candle, the boiling vinegar?
All here, and none of them the page’s counsel. Some discussions vacuum the flies off the walls and out of the air — they are weak fliers, those people say, and the hose catches them — with people unsure, one person each way, whether the flies die inside the machine, and one person’s warning that eggs can hatch in the bag if it is not emptied; some people prefer a flame for speed, and some people say the vacuum is easier and less unpleasant. Some people turn every light off but one, wait for the flies to gather on it, and take them with a lighter or a candle, and some people say the candle version is simpler; people’s own list of gaps includes what to do about curtains near a flame, and this page adds nothing to that except the obvious. People argue whether a pan of simmering vinegar kills them: some people say the fumes drop them in minutes, some people say it did nothing but burn their own eyes and made the flies livelier, people warn, one person each, the house smells of vinegar for hours and the fumes sting the eyes, and some people warn: do not do this in a home with a bird or a small mammal, because the fumes can harm them. One person sprays the flies out of the air with rubbing alcohol; one swats them with a racket; one says window screens keep the next generation out, and one person warns a trap does nothing about flies coming in from outside. If the flies are the big slow kind that ignore the vinegar, one person warns those are house flies and want a different page; the linked one is theirs.
Questions this step helps with
Full tip: https://findangel.org/tips/put-a-drop-of-soap-in-the-vinegar/ · FindAngel.org — free, always.