My vinegar fruit fly trap isn’t working. What else can I do?

Two things are usually going on. The trap needs a small fix so the flies cannot get back out. And a trap only ever catches adults, so if something in the kitchen is still breeding them, new flies hatch every day to replace the ones you catch. You have not failed, and you have probably done most of the work already. Here is the rest.

Fix the trap

• Use a bait they love. Apple cider vinegar works better than clear vinegar. A bit of very ripe fruit or a splash of wine works too.
• Add a drop of washing-up liquid. It breaks the surface of the liquid, so flies that land sink instead of walking off again. This is the step most traps are missing.
• Make the way in small. Cover the jar with cling film and poke a few small holes, or roll paper into a cone with a narrow tip. Easy in, hard out.
• Refresh it every few days. Old bait loses its smell.
• Put it where they gather, by the sink or bin. Not right next to the fruit bowl, which smells better than your trap.
• Use two or three if they gather in more than one spot.

Shop-bought fruit fly traps work the same way: a lure and a way in that is hard to find back out. They are tidier, not stronger.

Why the flies keep coming

If the trap catches plenty but you see as many flies as ever, something is still breeding them. Vacuuming the adults has the same limit. Even after a good clean, the usual hiding places are easy to miss: a drain, the bin’s lid seal, a sticky bottle in the recycling, a soft potato at the bottom of a bag, a spill under the fridge, a damp cloth. Our page fruit flies in a spotless kitchen goes through where to look, in order.

Test the drain

Drains are the source people miss most. To check, tape a clear plastic bag or cup over the plughole before bed. If there are flies trapped under it in the morning, they are coming from the drain. Scrub the inside of the pipe with a long, thin brush. Pouring bleach down runs past the film the larvae live in, and the brush is what removes it.

One week to break the cycle

1. Day one: remove anything soft or fermenting, rinse the recycling, wash the bin and its seal, and scrub the drains.
2. All week: every bit of fruit and veg goes in the fridge. Nothing left out for them to lay eggs in.
3. Every few days: refresh the traps and empty the kitchen bin.
4. End of the week: if numbers have dropped, keep going until they stop. If they have not, there is a source you have not found yet, or they are not fruit flies.

Kids and pets: a vinegar trap has no poison in it, but it is still not a drink. Put traps where pets and small children cannot knock them over or lap from them.

Are they actually fruit flies?

If a good trap catches almost nothing, check what you are dealing with. Fuzzy, moth-like flies on bathroom walls are drain flies, which vinegar does not lure well. See fruit fly or drain fly and drain flies that survive bleach. Small dark flies around houseplants are usually fungus gnats: see fungus gnats. The fruit fly guide shows the differences.